Performance information

• A type II toxin–antitoxin system, ECs3274-ECs3275, in enterohemorrhagic Escherichia coli O157
  Yuka Sasaki; Yuna Mogi; Mizuki Yoshioka; Ke Liu; Yuichi Otsuka
  Bioscience, Biotechnology, and Biochemistry, Volume：89, Number：1, First page：62, Last page：71, Jan. 2025, [Reviewed], [Last, Corresponding]
  Abstract
  
  The toxin–antitoxin (TA) genetic module controls various bacterial events. Novel toxins with different functions are still being discovered. This study aimed to determine whether the ECs3274-ECs3275 gene pair encoded by enterohemorrhagic Escherichia coli O157 functions as a TA system. To characterize this putative TA system, we analyzed the growth of E. coli expressing ECs3274, ECs3275, or both; the interaction between ECs3274 and ECs3275 using bacterial adenylate cyclase two-hybrid assays; and the DNA-binding ability of ECs3274 using gel-mobility shift assays. We observed that the ECs3274 antitoxin interacted with the ECs3275 toxin, was destabilized by Lon protease, and repressed its promoter activity via its helix-turn-helix (HTH) motif. These properties are consistent with those of typical type II TA antitoxins. Interestingly, ECs3275 has an HTH motif not observed in other TA toxins and is necessary for ECs3275 toxicity, suggesting that ECs3275 may exert its toxicity by regulating the expression of specific genes.
  Oxford University Press (OUP), Scientific journal
  DOI：https://doi.org/10.1093/bbb/zbae146
  DOI ID：10.1093/bbb/zbae146, eISSN：1347-6947
• Phage single-stranded DNA-binding protein or host DNA damage triggers the activation of the AbpAB phage defense system.　　　　　　　　　　　　　　　
  Takaomi Sasaki; Saya Takita; Takashi Fujishiro; Yunosuke Shintani; Satoki Nojiri; Ryota Yasui; Tetsuro Yonesaki; Yuichi Otsuka
  mSphere, Volume：8, Number：6, First page：e0037223, Dec. 2023, [Reviewed], [Last, Corresponding], ［International magazine］
  Although numerous phage defense systems have recently been discovered in bacteria, how these systems defend against phage propagation or sense phage infections remains unclear. The Escherichia coli AbpAB defense system targets several lytic and lysogenic phages harboring DNA genomes. A phage-encoded single-stranded DNA-binding protein, Gp32, activates this system similar to other phage defense systems such as Retron-Eco8, Hachiman, ShosTA, Nhi, and Hna. DNA replication inhibitors or defects in DNA repair factors activate the AbpAB system, even without phage infection. This is one of the few examples of activating phage defense systems without phage infection or proteins. The AbpAB defense system may be activated by sensing specific DNA-protein complexes.
  English, Scientific journal
  DOI：https://doi.org/10.1128/msphere.00372-23
  DOI ID：10.1128/msphere.00372-23, PubMed ID：37882551, PubMed Central ID：PMC10732053
• The hokW-sokW Locus Encodes a Type I Toxin–Antitoxin System That Facilitates the Release of Lysogenic Sp5 Phage in Enterohemorrhagic Escherichia coli O157
  Kosuke Takada; Kotone Hama; Takaomi Sasaki; Yuichi Otsuka
  Toxins, Volume：13, Number：11, First page：796, Last page：796, Nov. 2021, [Reviewed], [Last, Corresponding]
  The toxin-antitoxin (TA) genetic modules control various bacterial events, such as plasmid maintenance, persister cell formation, and phage defense. They also exist in mobile genetic elements, including prophages; however, their physiological roles remain poorly understood. Here, we demonstrate that hokW-sokW, a putative TA locus encoded in Sakai prophage 5 (Sp5) in enterohemorrhagic Escherichia coli O157: H7 Sakai strain, functions as a type I TA system. Bacterial growth assays showed that the antitoxic activity of sokW RNA against HokW toxin partially requires an endoribonuclease, RNase III, and an RNA chaperone, Hfq. We also demonstrated that hokW-sokW assists Sp5-mediated lysis of E. coli cells when prophage induction is promoted by the DNA-damaging agent mitomycin C (MMC). We found that MMC treatment diminished sokW RNA and increased both the expression level and inner membrane localization of HokW in a RecA-dependent manner. Remarkably, the number of released Sp5 phages decreased by half in the absence of hokW-sokW. These results suggest that hokW-sokW plays a novel role as a TA system that facilitates the release of Sp5 phage progeny through E. coli lysis.
  MDPI AG, English, Scientific journal
  DOI：https://doi.org/10.3390/toxins13110796
  DOI ID：10.3390/toxins13110796, eISSN：2072-6651, 共同研究・競争的資金等ID：13443555
• Manipulating Interactions between T4 Phage Long Tail Fibers and Escherichia coli Receptors
  Akiyo Suga; Marina Kawaguchi; Tetsuro Yonesaki; Yuichi Otsuka
  Applied and Environmental Microbiology, Volume：87, Number：13, Jul. 2021, [Reviewed], [Last, Corresponding]
  Understanding the host specificity of phages will lead to the development of phage therapy. The interaction between outer membrane protein C (OmpC), one of the Escherichia coli receptors, and the gp37 protein composing the digital tip (DT) region of the long tail fibers of bacteriophage T4 largely determines its host specificity.
  American Society for Microbiology, English, Scientific journal
  DOI：https://doi.org/10.1128/aem.00423-21
  DOI ID：10.1128/aem.00423-21, ISSN：0099-2240, eISSN：1098-5336, 共同研究・競争的資金等ID：13443555;13443556
• A short peptide derived from the ZorO toxin functions as an effective antimicrobial　　　　　　　　　　　　　　　
  Otsuka Y; Ishikawa T; Takahashi C; Masuda M
  Toxins, Volume：11, Number：7, First page：DOI:10.3390/toxins11070392, Jul. 2019, [Reviewed], [Lead, Corresponding], ［International magazine］
  Antimicrobial peptides are potential molecules for the development of novel antibiotic agents. The ZorO toxin of a type I toxin-antitoxin system in Escherichia coli O157:H7 is composed of 29 amino acids and its endogenous expression inhibits E. coli growth. However, little is known about its inhibitory mechanism. In this study, we demonstrate that the ZorO localized in the inner membrane affects the plasma membrane integrity and potential when expressed in E. coli cells, which triggers the production of cytotoxic hydroxyl radicals. We further show that five internal amino acids (Ala-Leu-Leu-Arg-Leu; ALLRL) of ZorO are necessary for its toxicity. This result prompted us to address the potential of the synthetic ALLRL peptide as an antimicrobial. Exogenously-added ALLRL peptide to Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis, and a fungus, Candida albicans, trigger cell membrane damage and exhibit growth defect, while having no effect on Gram-negative bacterium, E. coli. The ALLRL peptide retains its activity under the physiological salt concentrations, which is in contrast to natural antimicrobial peptides. Importantly, this peptide has no toxicity against mammalian cells. Taken together, an effective and short peptide, ALLRL, would be an attractive antimicrobial to Gram-positive bacteria and C. albicans.
  English, Scientific journal
  DOI：https://doi.org/10.3390/toxins11070392
  DOI ID：10.3390/toxins11070392, PubMed ID：31277504, PubMed Central ID：PMC6669753
• RnlB Antitoxin of the Escherichia coli RnlA-RnlB Toxin-Antitoxin Module Requires RNase HI for Inhibition of RnlA Toxin Activity　　　　　　　　　　　　　　　
  Kenta Naka; Dan Qi; Tetsuro Yonesaki; Yuichi Otsuka
  TOXINS, Volume：9, Number：1, First page：DOI:10.3390/toxins9010029, Jan. 2017, [Reviewed], [Last, Corresponding]
  The Escherichia coli RnlA-RnlB toxin-antitoxin system is related to the anti-phage mechanism. Under normal growth conditions, an RnlA toxin with endoribonuclease activity is inhibited by binding of its cognate RnlB antitoxin. After bacteriophage T4 infection, RnlA is activated by the disappearance of RnlB, resulting in the rapid degradation of T4 mRNAs and consequently no T4 propagation when T4 dmd encoding a phage antitoxin against RnlA is defective. Intriguingly, E. coli RNase HI, which plays a key role in DNA replication, is required for the activation of RnlA and stimulates the RNA cleavage activity of RnlA. Here, we report an additional role of RNase HI in the regulation of RnlA-RnlB system. Both RNase HI and RnlB are associated with NRD (one of three domains of RnlA). The interaction between RnlB and NRD depends on RNase HI. Exogenous expression of RnlA in wild-type cells has no effect on cell growth because of endogenous RnlB and this inhibition of RnlA toxicity requires RNase HI and NRD. These results suggest that RNase HI recruits RnlB to RnlA through NRD for inhibiting RnlA toxicity and thus plays two contrary roles in the regulation of RnlA-RnlB system.
  MDPI AG, English, Scientific journal
  DOI：https://doi.org/10.3390/toxins9010029
  DOI ID：10.3390/toxins9010029, ISSN：2072-6651, Web of Science ID：WOS:000392980000029
• Characterization of the interactions between Escherichia coli receptors, LPS and OmpC, and bacteriophage T4 long tail fibers　　　　　　　　　　　　　　　
  Ayaka Washizaki; Tetsuro Yonesaki; Yuichi Otsuka
  MICROBIOLOGYOPEN, Volume：5, Number：6, First page：1003, Last page：1015, Dec. 2016, [Reviewed], [Last, Corresponding]
  Bacteriophages have strict host specificity and the step of adsorption is one of key factors for determining host specificity. Here, we systematically examined the interaction between the Escherichia coli receptors lipopolysaccharide (LPS) and outer membrane protein C (OmpC), and the long tail fibers of bacteriophage T4. Using a variety of LPS mutants, we demonstrated that T4 has no specificity for the sugar sequence of the outer core (one of three LPS regions) in the presence of OmpC but, in the absence of OmpC, can adsorb to a specific LPS which has only one or two glucose residues without a branch. These results strengthen the idea that T4 adsorbs to E. coli via two distinct modes, OmpC-dependent and OmpC--independent, suggested by previous reports (Prehm et al. 1976; Yu and Mizushima 1982). Isolation and characterization of the T4 mutants Nik (No infection to K--12 strain), Nib (No infection to B strain), and Arl (altered recognition of LPS) identified amino acids of the long tail fiber that play important roles in the interaction with OmpC or LPS, suggesting that the top surface of the distal tip head domain of T4 long tail fibers interacts with LPS and its lateral surface interacts with OmpC.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1002/mbo3.384
  DOI ID：10.1002/mbo3.384, ISSN：2045-8827, Web of Science ID：WOS:000390567300008
• Structural insights into the inhibition mechanism of bacterial toxin LsoA by bacteriophage antitoxin Dmd　　　　　　　　　　　　　　　
  Hua Wan; Yuichi Otsuka; Zeng-Qiang Gao; Yong Wei; Zhen Chen; Michiaki Masuda; Tetsuro Yonesaki; Heng Zhang; Yu-Hui Dong
  MOLECULAR MICROBIOLOGY, Volume：101, Number：5, First page：757, Last page：769, Sep. 2016, [Reviewed], [Lead]
  Bacteria have obtained a variety of resistance mechanisms including toxin-antitoxin (TA) systems against bacteriophages (phages), whereas phages have also evolved to overcome bacterial anti-phage mechanisms. Dmd from T4 phage can suppress the toxicities of homologous toxins LsoA and RnlA from Escherichia coli, representing the first example of a phage antitoxin against multiple bacterial toxins in known TA systems. Here, the crystal structure of LsoA-Dmd complex showed Dmd is inserted into the deep groove between the N-terminal repeated domain (NRD) and the Dmd-binding domain (DBD) of LsoA. The NRD shifts significantly from a 'closed' to an 'open' conformation upon Dmd binding. Site-directed mutagenesis of Dmd revealed the conserved residues (W31 and N40) are necessary for LsoA binding and the toxicity suppression as determined by pull-down and cell toxicity assays. Further mutagenesis identified the conserved Dmd-binding residues (R243, E246 and R305) of LsoA are vital for its toxicity, and suggested Dmd and LsoB may possess different inhibitory mechanisms against LsoA toxicity. Our structure-function studies demonstrate Dmd can recognize LsoA and inhibit its toxicity by occupying the active site possibly via substrate mimicry. These findings have provided unique insights into the defense and counter-defense mechanisms between bacteria and phages in their co-evolution.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1111/mmi.13420
  DOI ID：10.1111/mmi.13420, ISSN：0950-382X, eISSN：1365-2958, Web of Science ID：WOS:000384410300005
• Prokaryotic toxin-antitoxin systems: novel regulations of the toxins　　　　　　　　　　　　　　　
  Yuichi Otsuka
  CURRENT GENETICS, Volume：62, Number：2, First page：379, Last page：382, May 2016, [Reviewed], [Lead, Corresponding]
  Toxin-antitoxin (TA) systems are widely conserved in prokaryotic plasmids and chromosomes and are linked to many roles in cell physiology, including plasmid maintenance, stress response, persistence and protection from phage infection. A TA system is composed of a stable toxin and a labile antitoxin that inhibits a harmful effect of the cognate toxin. When gene expression from the TA loci is repressed under certain conditions such as nutrient starvation, the toxin is freed from the rapidly degrading antitoxin and obstructs an essential cellular process, such as DNA replication, translation and peptidoglycan synthesis, which subsequently causes growth arrest. TA systems are classified into five types according to the nature and the function of antitoxins, and the activity of toxins is tightly regulated in a variety of ways. This short-review highlights several novel regulatory mechanisms for Escherichia coli toxins that we recently discovered.
  SPRINGER, English, Scientific journal
  DOI：https://doi.org/10.1007/s00294-015-0557-z
  DOI ID：10.1007/s00294-015-0557-z, ISSN：0172-8083, eISSN：1432-0983, Web of Science ID：WOS:000373954800022
• An ADP-ribosyltransferase Alt of bacteriophage T4 negatively regulates the Escherichia coli MazF toxin of a toxin-antitoxin module　　　　　　　　　　　　　　　
  Abdulraheem M. Alawneh; Dan Qi; Tetsuro Yonesaki; Yuichi Otsuka
  MOLECULAR MICROBIOLOGY, Volume：99, Number：1, First page：188, Last page：198, Jan. 2016, [Reviewed], [Last, Corresponding]
  Prokaryotic toxin-antitoxin (TA) systems are linked to many roles in cell physiology, such as plasmid maintenance, stress response, persistence and protection from phage infection, and the activities of toxins are tightly regulated. Here, we describe a novel regulatory mechanism for a toxin of Escherichia coli TA systems. The MazF toxin of MazE-MazF, which is one of the best characterized type II TA systems, was modified immediately after infection with bacteriophage T4. Mass spectrometry demonstrated that the molecular weight of this modification was 542 Da, corresponding to a mono-ADP-ribosylation. This modification disappeared in cells infected with T4 phage lacking Alt, which is one of three ADP-ribosyltransferases encoded by T4 phage and is injected together with phage DNA upon infection. In vivo and in vitro analyses confirmed that T4 Alt ADP-ribosylated MazF at an arginine residue at position 4. Finally, the ADPribosylation of MazF by Alt resulted in the reduction of MazF RNA cleavage activity in vitro, suggesting that it may function to inactivate MazF during T4 infection. This is the first example of the chemical modification of an E. coli toxin in TA systems to regulate activity.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1111/mmi.13225
  DOI ID：10.1111/mmi.13225, ISSN：0950-382X, eISSN：1365-2958, Web of Science ID：WOS:000369157900013
• Rapid Degradation of Host mRNAs by Stimulation of RNase E Activity by Srd of Bacteriophage T4　　　　　　　　　　　　　　　
  Dan Qi; Abdulraheem M. Alawneh; Tetsuro Yonesaki; Yuichi Otsuka
  GENETICS, Volume：201, Number：3, First page：977, Last page：U356, Nov. 2015, [Reviewed], [Last, Corresponding]
  Escherichia coli messenger RNAs (mRNAs) are rapidly degraded immediately after bacteriophage T4 infection, and the host RNase E contributes to this process. Here, we found that a previously uncharacterized factor of T4 phage, Srd (Similarity with rpoD), was involved in T4-induced host mRNA degradation. The rapid decay of ompA and lpp mRNAs was partially alleviated and a decay intermediate of lpp mRNA rapidly accumulated in cells infected with T4 phage lacking srd. Exogenous expression of Srd in uninfected cells significantly accelerated the decay of these mRNAs. In addition, lpp(T) RNA, with a sequence identical to the decay intermediate of lpp mRNA and a triphosphate at 5'-end, was also destabilized by Srd. The destabilization of these RNAs by Srd was not observed in RNase E-defective cells. The initial cleavage of a primary transcript by RNase E can be either direct or dependent on the 5'-end of transcript. In the latter case, host RppH is required to convert the triphosphate at 5'-end to a monophosphate. lpp(T) RNA, but not lpp and ompA mRNAs, required RppH for Srd-stimulated degradation, indicating that Srd stimulates both 5'-end-dependent and -independent cleavage activities of RNase E. Furthermore, pull-down and immunoprecipitation analyses strongly suggested that Srd physically associates with the N-terminal half of RNase E containing the catalytic moiety and the membrane target sequence. Finally, the growth of T4 phage was significantly decreased by the disruption of srd. These results strongly suggest that the stimulation of RNase E activity by T4 Srd is required for efficient phage growth.
  GENETICS SOCIETY AMERICA, English, Scientific journal
  DOI：https://doi.org/10.1534/genetics.115.180364
  DOI ID：10.1534/genetics.115.180364, ISSN：0016-6731, eISSN：1943-2631, Web of Science ID：WOS:000365517200014
• AbpA and AbpB provide anti-phage activity in Escherichia coli　　　　　　　　　　　　　　　
  Ryota Yasui; Ayaka Washizaki; Yuko Furihata; Tetsuro Yonesaki; Yuichi Otsuka
  Genes and Genetic Systems, Volume：89, Number：2, First page：51, Last page：60, Sep. 2014, [Reviewed], [Last, Corresponding]
  Bacteria have a variety of resistance mechanisms for surviving bacteriophage infections. Here, we describe a novel anti-phage mechanism in Escherichia coli.Cells harboring a plasmid with the genes abpA and abpB, formerly yfjL and yfjK, blocked the propagation of bacteriophages belonging to three families: T4, T2, T7 and λ phages. Both genes were necessary for the inhibition of phage propagation, and deletion of either chromosomal gene resulted in a 20% increase of progeny compared to wild-type cells. Neither overexpression nor deficiency of AbpA and AbpB had any apparent effect on E. coli growth. We isolated seven suppressor mutants of T4 phage that grew weakly on cells overexpressing AbpA and AbpB, and found that their mutations were all located in gene 41, which encodes a replicative DNA helicase that is essential for DNA replication. Furthermore, we demonstrated that AbpA and AbpB inhibited DNA replication and late gene expression of T4 phage. Similarly, DNA replication of T7 and λ phages was also inhibited by AbpA and AbpB. These results strongly suggest that E. coli AbpA and AbpB target DNA replication of phages to block their propagation.
  Genetics Society of Japan, English, Scientific journal
  DOI：https://doi.org/10.1266/ggs.89.51
  DOI ID：10.1266/ggs.89.51, ISSN：1880-5779, PubMed ID：25224971, SCOPUS ID：84907545882
• RNase HI stimulates the activity of RnlA toxin in Escherichia coli　　　　　　　　　　　　　　　
  Kenta Naka; Mitsunori Koga; Tetsuro Yonesaki; Yuichi Otsuka
  MOLECULAR MICROBIOLOGY, Volume：91, Number：3, First page：596, Last page：605, Feb. 2014, [Reviewed], [Last, Corresponding]
  A type II toxin-antitoxin system in Escherichia coli, rnlA-rnlB, functions as an anti-phage mechanism. RnlA is a toxin with an endoribonuclease activity and the cognate RnlB inhibits RnlA toxicity in E. coli cells. After bacteriophage T4 infection, RnlA is activated by the disappearance of RnlB, resulting in the rapid degradation of T4 mRNAs and consequently no T4 propagation, when T4 dmd is defective: Dmd is an antitoxin against RnlA for promoting own propagation. Previous studies suggested that the activation of RnlA after T4 infection was regulated by multiple components. Here, we provide the evidence that RNase HI is an essential factor for activation of RnlA. The dmd mutant phage could grow on Delta rnhA (encoding RNase HI) cells, in which RnlA-mediated mRNA cleavage activity was defective. RNase HI bound to RnlA in vivo and enhanced the RNA cleavage activity of RnlA in vitro. In addition, ectopic expression of RnlA in Delta rnlAB Delta rnhA cells has less effect on cell toxicity and RnlA-mediated mRNA degradation than in Delta rnlAB cells. This is the first example of a direct factor for activation of a toxin.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1111/mmi.12479
  DOI ID：10.1111/mmi.12479, ISSN：0950-382X, eISSN：1365-2958, Web of Science ID：WOS:000345498000012
• Structure-function studies of Escherichia coli RnlA reveal a novel toxin structure involved in bacteriophage resistance　　　　　　　　　　　　　　　
  Yong Wei; Zeng-Qiang Gao; Yuichi Otsuka; Kenta Naka; Tetsuro Yonesaki; Heng Zhang; Yu-Hui Dong
  MOLECULAR MICROBIOLOGY, Volume：90, Number：5, First page：956, Last page：965, Dec. 2013, [Reviewed]
  Escherichia coli RnlA-RnlB is a newly identified toxin-antitoxin (TA) system that plays a role in bacteriophage resistance. RnlA functions as a toxin with mRNA endoribonuclease activity and the cognate antitoxin RnlB inhibits RnlA toxicity in E. coli cells. Interestingly, T4 phage encodes the antitoxin Dmd, which acts against RnlA to promote its own propagation, suggesting that RnlA-Dmd represents a novel TA system. Here, we have determined the crystal structure of RnlA refined to 2.10 angstrom. RnlA is composed of three independent domains: NTD (N-terminal domain), NRD (N repeated domain) and DBD (Dmd-binding domain), which is an organization not previously observed among known toxin structures. Small-angle X-ray scattering (SAXS) analysis revealed that RnlA forms a dimer in solution via interactions between the DBDs from both monomers. The in vitro and in vivo functional studies showed that among the three domains, only the DBD is responsible for recognition and inhibition by Dmd and subcellular location of RnlA. In particular, the helix located at the C-terminus of DBD plays a vital role in binding Dmd. Our comprehensive studies reveal the key region responsible for RnlA toxicity and provide novel insights into its structure-function relationship.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1111/mmi.12409
  DOI ID：10.1111/mmi.12409, ISSN：0950-382X, eISSN：1365-2958, Web of Science ID：WOS:000327374300004
• Identification of the human PMR1 mRNA endonuclease as an alternatively processed product of the gene for peroxidasin-like protein　　　　　　　　　　　　　　　
  Shan-Qing Gu; Baskar Bakthavachalu; Joonhee Han; Deepak P. Patil; Yuichi Otsuka; Chittibabu Guda; Daniel R. Schoenberg
  RNA, Volume：18, Number：6, First page：1186, Last page：1196, Jun. 2012, [Reviewed]
  The PMR1 endonuclease was discovered in Xenopus liver and identified as a member of the large and diverse peroxidase gene family. The peroxidase genes arose from multiple duplication and rearrangement events, and their high degree of sequence similarity confounded attempts to identify human PMR1. The functioning of PMR1 in mRNA decay depends on the phosphorylation of a tyrosine in the C-terminal polysome targeting domain by c-Src. The sequences of regions that are required for c-Src binding and phosphorylation of Xenopus PMR1 were used to inform a bioinformatics search that identified two related genes as potential candidates for human PMR1: peroxidasin homolog (PXDN) and peroxidasin homolog-like (PXDNL) protein. Although each of these genes is predicted to encode a large, multidomain membrane-bound peroxidase, alternative splicing of PXDNL pre-mRNA yields a transcript whose predicted product is a 57-kDa protein with 42% sequence identity to Xenopus PMR1. Results presented here confirm the existence of the predicted 57-kDa protein, show this is the only form of PXDNL detected in any of the human cell lines examined, and confirm its identity as human PMR1. Like the Xenopus protein, human PMR1 binds to c-Src, is tyrosine phosphorylated, sediments on polysomes, and catalyzes the selective decay of a PMR1 substrate mRNA. Importantly, the expression of human PMR1 stimulates cell motility in a manner similar to that of the Xenopus PMR1 expressed in human cells, thus providing definitive evidence linking endonuclease decay to the regulation of cell motility.
  COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT, English, Scientific journal
  DOI：https://doi.org/10.1261/rna.031369.111
  DOI ID：10.1261/rna.031369.111, ISSN：1355-8382, eISSN：1469-9001, Web of Science ID：WOS:000304423000008
• Dmd of bacteriophage T4 functions as an antitoxin against Escherichia coli LsoA and RnlA toxins　　　　　　　　　　　　　　　
  Yuichi Otsuka; Tetsuro Yonesaki
  MOLECULAR MICROBIOLOGY, Volume：83, Number：4, First page：669, Last page：681, Feb. 2012, [Reviewed], [Lead]
  Enterohaemorrhagic Escherichia coli O157:H7 harbours a cryptic plasmid, pOSAK1, that carries only three ORFs: mobA (involved in plasmid mobilization), ORF1 and ORF2. Predicted proteins encoded by these two ORFs were found to share a weak homology with RnlA and RnlB, respectively, a toxinantitoxin system encoded on the E. coli K-12 chromosome. Here, we report that lsoA (ORF1) encodes a toxin and lsoB (ORF2) an antitoxin. In spite of the homologies, RnlB and LsoB functioned as antitoxins against only their cognate toxins and not interchangeably with each other. Interestingly, T4 phage Dmd suppressed the toxicities of both RnlA and LsoA by direct interaction, the first example of a phage with an antitoxin against multiple toxins.
  WILEY-BLACKWELL, English, Scientific journal
  DOI：https://doi.org/10.1111/j.1365-2958.2012.07975.x
  DOI ID：10.1111/j.1365-2958.2012.07975.x, ISSN：0950-382X, Web of Science ID：WOS:000299779200002
• Escherichia coli rnlA and rnlB Compose a Novel Toxin-Antitoxin System　　　　　　　　　　　　　　　
  Mitsunori Koga; Yuichi Otsuka; Sebastien Lemire; Tetsuro Yonesaki
  GENETICS, Volume：187, Number：1, First page：123, Last page：130, Jan. 2011, [Reviewed]
  RNase LS was originally identified as a potential antagonist of bacteriophage T4 infection. When T4 dmd is defective, RNase LS activity rapidly increases after T4 infection and cleaves T4 mRNAs to antagonize T4 reproduction. Here we show that rnlA, a structural gene of RNase LS, encodes a novel toxin, and that rnlB (formally yfjO), located immediately downstream of rnlA, encodes an antitoxin against RnlA. Ectopic expression of RnlA caused inhibition of cell growth and rapid degradation of mRNAs in Delta rnlAB cells. On the other hand, RnlB neutralized these RnlA effects. Furthermore, overexpression of RnlB in wild-type cells could completely suppress the growth defect of a T4 dmd mutant, that is, excess RnlB inhibited RNase LS activity. Pull-down analysis showed a specific interaction between RnlA and RnlB. Compared to RnlA, RnlB was extremely unstable, being degraded by ClpXP and Lon proteases, and this instability may increase RNase LS activity after T4 infection. All of these results suggested that rnlA-rnlB define a new toxin-antitoxin (TA) system.
  GENETICS SOC AM, English, Scientific journal
  DOI：https://doi.org/10.1534/genetics.110.121798
  DOI ID：10.1534/genetics.110.121798, ISSN：0016-6731, Web of Science ID：WOS:000286100900010
• IscR Regulates RNase LS Activity by Repressing rnlA Transcription　　　　　　　　　　　　　　　
  Yuichi Otsuka; Kumiko Miki; Mitsunori Koga; Natsu Katayama; Wakako Morimoto; Yasuhiro Takahashi; Tetsuro Yonesaki
  GENETICS, Volume：185, Number：3, First page：823, Last page：830, Jul. 2010, [Reviewed], [Lead]
  The Escherichia coli endoribonuclease LS was originally identified as a potential antagonist of bacteriophage T4. When the T4 dmd gene is defective, RNase LS cleaves T4 mRNAs and antagonizes T4 reproduction. This RNase also plays an important role in RNA metabolisms in E. coli. rnlA is an essential gene for RNase LS activity, but the transcriptional regulation of this gene remains to be elucidated. An Fe-S cluster protein, IscR, acts as a transcription factor and controls the expression of genes that are necessary for Fe-S cluster biogenesis. Here, we report that overexpression of IscR suppressed RNase LS activity, causing the loss of antagonist activity against phage T4. This suppressive effect did not require the ligation of Fe-S cluster into IscR. beta-Galactosidase reporter assays showed that transcription from an rnlA promoter increased in iscR-deleted cells compared to wild-type cells, and gel-mobility shift assays revealed specific binding of IscR to the rnlA promoter region. RT-PCR analysis demonstrated that endogenous rnlA mRNA was reduced by overexpression of IscR and increased by deletion of iscR. From these results, we conclude that IscR negatively regulates transcription of rnlA and represses RNase LS activity.
  GENETICS SOC AM, English, Scientific journal
  DOI：https://doi.org/10.1534/genetics.110.114462
  DOI ID：10.1534/genetics.110.114462, ISSN：0016-6731, Web of Science ID：WOS:000281906800010
• 新世代のファージ研究　　　　　　　　　　　　　　　
  米崎哲朗; 大塚裕一
  Volume：62, First page：55, Last page：58, 2010, [Last]
  Japanese, Research institution
• Identification of a Cytoplasmic Complex That Adds a Cap onto 5 '-Monophosphate RNA　　　　　　　　　　　　　　　
  Yuichi Otsuka; Nancy L. Kedersha; Daniel R. Schoenberg
  MOLECULAR AND CELLULAR BIOLOGY, Volume：29, Number：8, First page：2155, Last page：2167, Apr. 2009, [Reviewed], [Lead]
  Endonuclease decay of nonsense-containing beta-globin mRNA in erythroid cells generates 5'-truncated products that were reported previously to have a cap or caplike structure. We confirmed that this 5' modification is indistinguishable from the cap on full-length mRNA, and Western blotting, immunoprecipitation, and active-site labeling identified a population of capping enzymes in the cytoplasm of erythroid and nonerythroid cells. Cytoplasmic capping enzyme sediments in a 140-kDa complex that contains a kinase which, together with capping enzyme, converts 5'-monophosphate RNA into 5'-GpppX RNA. Capping enzyme shows diffuse and punctate staining throughout the cytoplasm, and its staining does not overlap with P bodies or stress granules. Expression of inactive capping enzyme in a form that is restricted to the cytoplasm reduced the ability of cells to recover from oxidative stress, thus supporting a role for capping in the cytoplasm and suggesting that some mRNAs may be stored in an uncapped state.
  AMER SOC MICROBIOLOGY, English, Scientific journal
  DOI：https://doi.org/10.1128/MCB.01325-08
  DOI ID：10.1128/MCB.01325-08, ISSN：0270-7306, Web of Science ID：WOS:000264558400015
• APPROACHES FOR STUDYING PMR1 ENDONUCLEASE-MEDIATED MRNA DECAY　　　　　　　　　　　　　　　
  Yuichi Otsuka; Daniel R. Schoenberg
  RNA TURNOVER IN EUKARYOTES: NUCLEASES, PATHWAYS AND ANAYLSIS OF MRNA DECAY, Volume：448, First page：241, Last page：263, 2008, [Reviewed], [Lead]
  Although most eukaryotic mRNAs are degraded by exonucleases acting on either end of the molecule, a subset of mRNAs undergo endonuclease cleavage within the mRNA body. Endonuclease cleavage can be activated by cellular stress, extracellular signals, or by ribosome stalling, as might occur at a premature termination codon. Only a few eukaryotic mRNA endonucleases have been identified, and of these, polysomal ribonuclease 1 (PMR1) is the best characterized. A notable feature of PMR1-mediated mRNA decay is that it acts on specific mRNAs while they are engaged by translating ribosomes. This chapter begins with several procedures used to characterize in vivo endonuclease cleavage of any mRNA by any endonudease. These include approaches for identifying the 5'-end(s) downstream of an endonuclease cleavage site (S1 nuclease protection and primer extension), and a ligation-mediated RT-PCR approach developed in our laboratory for identifying the 3'-ends upstream of a cleavage site. We then describe a number of approaches used to characterize PMR1-mediated mRNA decay in cultured cells. PMR1 participates in a number of different complexes. We show several approaches for studying these complexes, and we describe techniques for isolating and characterizing PMR1-interacting proteins and its target mRNAs. Although the various techniques described here have proven their usefulness in studying PMR1, they can be generalized to studying decay by any other mRNA endonuclease.
  ELSEVIER ACADEMIC PRESS INC, English, In book
  DOI：https://doi.org/10.1016/S0076-6879(08)02613-X
  DOI ID：10.1016/S0076-6879(08)02613-X, ISSN：0076-6879, Web of Science ID：WOS:000262252300013
• A role of Rn1A in the RNase LS activity from Escherichia coli　　　　　　　　　　　　　　　
  Yuichi Otsuka; Mitsunori Koga; Akira Iwamoto; Tetsuro Yonesaki
  GENES & GENETIC SYSTEMS, Volume：82, Number：4, First page：291, Last page：299, Aug. 2007, [Reviewed], [Lead]
  Escherichia coli ribonuclease LS is a potential antagonist of bacteriophage T4. When the T4 dmd gene is defective, RNase LS cleaves T4 mRNAs and antagonizes T4 reproduction. Our previous work demonstrated that E. coli rnlA is essential for RNase LS activity. Here we show that His-tagged RnlA cleaves T4 soc RNA at one of the sites also cleaved by RNase LS in a cell extract. The cleavage activities of His-tagged RnlA and the RNase LS activity in a cell extract were inhibited by Dmd encoded by T4 phage. Fractionation of the RNase LS activity in a cell extract showed that it sedimented through a sucrose density gradient as a 1000-kDa complex that included RnlA. Pull-down experiments revealed more than 10 proteins associated with His-tagged RnlA. Among these, triose phosphate isomerase exhibited a remarkable affinity to RnlA. These results suggest that RnlA plays a central role in RNase LS activity and that its activity is regulated by multiple components.
  GENETICS SOC JAPAN, English, Scientific journal
  ISSN：1341-7568, eISSN：1880-5779, Web of Science ID：WOS:000250609000003
• Polysome-bound endonuclease PMR1 is targeted to stress granules via stress-specific binding to TIA-1　　　　　　　　　　　　　　　
  Feng Yang; Yong Peng; Elizabeth L. Murray; Yuichi Otsuka; Nancy Kedersha; Daniel R. Schoenberg
  MOLECULAR AND CELLULAR BIOLOGY, Volume：26, Number：23, First page：8803, Last page：8813, Dec. 2006, [Reviewed]
  The generalized process of mRNA decay involves deadenylation followed by release from translating polysomes, decapping, and exonuclease decay of the mRNA body. In contrast the mRNA endonuclease PMR1 forms a selective complex with its translating substrate mRNA, where it initiates decay by cleaving within the mRNA body. In stressed cells the phosphorylation of the alpha subunit of eukaryotic initiation factor 2 causes translating mRNAs to accumulate with stalled 48S subunits in large subcellular structures termed stress granules (SGs), wherein mRNAs undergo sorting for reinitiation, storage, or decay. Given the unique relationship between translation and PMR1-mediated mRNA decay, we examined the impact of stress-induced dissociation of polysomes on this process. Arsenite stress disrupts the polysome binding of PMR1 and its substrate mRNA but has no impact on the critical tyrosine phosphorylation of PMR1, its association with substrate mRNA, or its association with the functional similar to 680-kDa mRNP complex in which it normally resides on polysomes. We show that arsenite stress drives PMR1 into an RNase-resistant complex with TIA-1, and we identify a distinct domain in the N terminus of PMR1 that facilitates its interaction with TIA-1. Finally, we show that arsenite promotes the delayed association of PMR1 with SGs under conditions which cause tristetraprolin and butyrate response factor 1, proteins that facilitate exonucleolytic mRNA, to exit SGs.
  AMER SOC MICROBIOLOGY, English, Scientific journal
  DOI：https://doi.org/10.1128/MCB.00090-06
  DOI ID：10.1128/MCB.00090-06, ISSN：0270-7306, Web of Science ID：WOS:000242203700012
• A novel endoribonuclease, RNase LS, in Escherichia coli.　　　　　　　　　　　　　　　
  Otsuka Y; Yonesaki T
  Genetics, Volume：169, First page：13, Last page：20, Jan. 2005, [Reviewed], [Lead]
  English, Scientific journal
  CiNii Articles ID：10024394672
• A Novel Endoribonuclease of Escherichia coli that Induces Gene Silencing in Bacteriophage T4　　　　　　　　　　　　　　　
  Yuichi Otsuka
  Osaka University, Dec. 2003, [Lead, Corresponding]
  English, Doctoral thesis
• 大腸菌mRNAの分解　　　　　　　　　　　　　　　
  大塚裕一; 米崎哲朗
  Volume：48, Number：3, First page：240, Last page：246, Mar. 2003, [Reviewed], [Lead]
  Japanese, Others
  ISSN：0039-9450, CiNii Articles ID：40005690889, CiNii Books ID：AN00140437
• Escherichia coli endoribonucleases involved in cleavage of bacteriophage T4 mRNAs　　　　　　　　　　　　　　　
  Y Otsuka; H Ueno; T Yonesaki
  JOURNAL OF BACTERIOLOGY, Volume：185, Number：3, First page：983, Last page：990, Feb. 2003, [Reviewed], [Lead]
  The dmd mutant of bacteriophage T4 has a defect in growth because of rapid degradation of late-gene mRNAs, presumably caused by mutant-specific cleavages of RNA. Some such cleavages can occur in an allele-specific manner, depending on the translatability of RNA or the presence of a termination codon. Other cleavages are independent of translation. In the present study, by introducing plasmids carrying various soc alleles, we could detect cleavages of soc RNA in uninfected cells identical to those found in dmd mutant-infected cells. We isolated five Escherichia coli mutant strains in which the dmd mutant was able to grow. One of these strains completely suppressed the dmd mutant-specific cleavages of soc RNA. The loci of the E. coli mutations and the effects of mutations in known RNase-encoding genes suggested that an RNA cleavage activity causing the dmd mutant-specific mRNA degradation is attributable to a novel RNase. In addition, we present evidence that 5'-truncated soc RNA, a stable form in T4-infected cells regardless of the presence of a dmd mutation, is generated by RNase E.
  AMER SOC MICROBIOLOGY, English, Scientific journal
  DOI：https://doi.org/10.1128/JB.185.3.983-990.2003
  DOI ID：10.1128/JB.185.3.983-990.2003, ISSN：0021-9193, Web of Science ID：WOS:000180834300031
• Gene 61.3 of bacteriophage t4 is the spackle gene　　　　　　　　　　　　　　　
  T Kai; H Ueno; Y Otsuka; W Morimoto; T Yonesaki
  VIROLOGY, Volume：260, Number：2, First page：254, Last page：259, Aug. 1999, [Reviewed]
  The bacteriophage T4 e gene encodes lysozyme (e-lysozyme), which releases progeny phage after normal infection of Escherichia coli cells. A mutation in the spackle gene suppresses the defect in e-lysozyme (Emrich, 1968). The spackle gene was mapped between genes 41 and 61, but its precise location has not previously been determined. In the current study, we constructed an amber mutant of gene 61.3, amST14, by site-directed mutagenesis. The gene 61.3 mutant shares phenotypes with spackle mutants: The amST14 mutant forms large plaques with sharp edges and exhibits truncated lysis inhibition, and furthermore, the mutation can suppress the defect in e-lysozyme activity. In addition, cloned gene 61.3 can rescue (by homologous recombination) as well as complement the S12 mutation in the spackle gene. These results strongly suggest that gene 61.3 is the spackle gene. Indeed, the S12 mutant has one base deletion of five in a consecutive A tract in the gene 61.3 coding region, substituting an unrelated 6-amino acid sequence for the 9 C-terminal amino acids in the gene 61.3 protein. The gene 61.3 protein is predicted to localize in the periplasmic space after cleavage of a signal sequence. (C) 1999 Academic Press.
  ACADEMIC PRESS INC, English, Scientific journal
  ISSN：0042-6822, Web of Science ID：WOS:000082027100005

• RNA Damage and Repair　　　　　　　　　　　　　　　
  Yuichi Otsuka, [Joint work], Endoribonucleases of the toxin-antitoxin systems induce abortive infection
  Kotta-Loizou Ioly・Springer, Jul. 2021
  ISBN：9783030765712, 共同研究・競争的資金等ID：36529828;13443556

• 細菌とファージの生存競争　　　　　　　　　　　　　　　
  大塚裕一
  Mar. 2023, [Invited]
  Invited oral presentation
• The arms race between bacteria and phages ~toxin–antitoxin systems~　　　　　　　　　　　　　　　
  Yuichi Otsuka
  Nov. 2018, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• この世はウイルスだらけ　　　　　　　　　　　　　　　
  大塚裕一
  Dec. 2017, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• 細菌とファージの生存戦略：トキシン－アンチトキシン系の制御　　　　　　　　　　　　　　　
  大塚裕一
  Dec. 2016, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• 細菌のトキシン－アンチトキシン系とファージ感染との関係　　　　　　　　　　　　　　　
  大塚裕一
  Mar. 2016, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• ファージ療法・T4ファージを用いた新しいチャレンジ　　　　　　　　　　　　　　　
  大塚裕一
  Sep. 2014, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• Toxin–Antitoxin Systems in Escherichia coli O157 and Bacteriophage T4 Infection　　　　　　　　　　　　　　　
  Yuichi Otsuka
  Jul. 2012, [Invited], [International conference]
  English, Oral presentation
• トキシン－アンチトキシンとT4ファージ　　　　　　　　　　　　　　　
  大塚裕一
  Sep. 2010, [Invited], [Domestic conference]
  Japanese, Invited oral presentation
• 5' capping of endonuclease-generated decay intermediates by a cytoplasmic capping enzyme complex　　　　　　　　　　　　　　　
  Yuichi Otsuka
  Keystone Symposia 2008: Translational Regulatory Mechanisms, Jan. 2010, [Invited], [International conference]
  English, Invited oral presentation

• Present
• Present
• Present
• Present, JAPANESE SOCIETY FOR BACTERIOLOGY
• Present, THE MOLECULAR BIOLOGY SOCIETY OF JAPAN

• A novel antiphage mechanism suppresses the spread of drug-resistant bacteria　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), 01 Apr. 2023 - 31 Mar. 2026
  Saitama University
  Grant amount(Total)：4810000, Direct funding：3700000, Indirect funding：1110000
  Grant number：23K06526
• The toxin–antitoxin systems suppress the expansion of antimicrobial resistant bacteria　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Apr. 2020 - Mar. 2024
  Saitama University, Principal investigator
  Grant amount(Total)：4290000, Direct funding：3300000, Indirect funding：990000
  Grant number：20K07493
  書籍等出版物ID：36829728
• Repression of the spread of antimicrobial resistant bacteria and pathogenic bacteria using the bacterial toxin-antitoxin system　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Apr. 2017 - Mar. 2021
  Otsuka Yuichi, Principal investigator
  Grant amount(Total)：4810000, Direct funding：3700000, Indirect funding：1110000
  The toxin-antitoxin (TA) system is a genetic module composed of a toxin and its cognate antitoxin. The ZorO toxin in Escherichia coli O157 is composed of 29 amino acids and its endogenous expression inhibits E. coli growth. Here, we demonstrated that the ZorO localized in the inner membrane affects the plasma membrane integrity. We further showed that five internal amino acids (Ala-Leu-Leu-Arg-Leu; ALLRL) of ZorO are necessary for its toxicity. Exogenously-added ALLRL peptide to Gram-positive bacteria, S. aureus and B. subtilis, and a fungus, C. albicans, trigger cell membrane damage and exhibit growth defect. Importantly, this peptide has no toxicity against mammalian cells. Taken together, an effective and short peptide, ALLRL, would be an attractive antimicrobial to Gram-positive bacteria and C. albicans. Furthermore, we demonstrated that the TA system suppresses the transduction which is one of the mechanisms that lead to the horizontal gene transfer.
  Grant number：17K08837
  論文ID：36529263
• The functional analysis and the application of bacterial toxin-antitoxin system　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Grant-in-Aid for Young Scientists (B), Apr. 2013 - Mar. 2017
  Otsuka Yuichi; TADA Shunsuke; TAKAHASHI Chisato, Principal investigator
  Grant amount(Total)：4420000, Direct funding：3400000, Indirect funding：1020000
  Toxin-antitoxin system (TAS) is widely conserved in prokaryotic plasmids and chromosomes and is linked to many roles in cell physiology. TAS is composed of a stable toxin that inhibits one of essential cellular processes, and a labile antitoxin that inhibits a harmful effect of the cognate toxin. In this study, the new TAS, z3289-sRNA1, encoded by the Enterohemorrhagic E. coli O157:H7 chromosome has been characterized. I elucidated the molecular mechanism of the toxicity caused by the z3289 toxin, the mechanism for the translational repression of the z3289 toxin by the sRNA1 antitoxin, and the physiological role of z3289-sRNA1 as an anti-phage defense. In addition, I demonstrated that the modified z3289 toxin functions as an antimicrobial peptide.
  Grant number：25870386
  論文ID：36529314, 書籍等出版物ID：36829728
• Inspection of mechanism for recognition of host by phage　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Apr. 2011 - Mar. 2015
  YONESAKI Tetsuro; OTSUKA Yuichi, Osaka University, Coinvestigator
  Grant amount(Total)：5200000, Direct funding：4000000, Indirect funding：1200000
  T4 adsorption to E. coli K12 strain depends on the presence of OmpC, but T4 can adsorb to B strain independently of OmpC. Using K12 mutants defective in various genes required for LPS synthesis, we systematically analyzed the adsorption of T4 phage to these mutants dependent on or independent of OmpC. Furthermore, we isolated T4 mutants which can adsorb to B strain but not to K12 strain or vice versa. These results strongly suggest that T4 has two different mechanisms for adsorption to host cells. In addition, present study identified specific structures in OmpC and the distal tip of T4 long tail fiber, required for the recognition of OmpC by T4.
  Grant number：23570211
• Relationship of cytoplasmic capping to translation and cell stress　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity Start-up, Grant-in-Aid for Research Activity Start-up, Apr. 2009 - Mar. 2011
  OTSUKA Yuichi, Osaka University, Principal investigator
  Grant amount(Total)：2574000, Direct funding：1980000, Indirect funding：594000
  The purpose of this research project is to verify that capping can occur in cytoplasm as well as nucleus, and show the significance of cytoplasmic capping in gene expression. I identified many target mRNAs to which cap structures would be added in cytoplasm. Also, deep sequencing analysis suggested that some of these mRNAs might have poly(U) tail at 3' terminus. These modifications on mRNA may play important roles in gene expression. In a different research project, I showed that bacteriophage T4 had an antitoxin against E.coli toxins for its own survival.
  Grant number：21870020
• Relationship of cytoplasmic capping to translation and cell stress　　　　　　　　　　　　　　　
  American Heart Association, Grants-in-Aid for Scientific Research, Grant-in-Aid for Research Activity Start-up, Jul. 2008 - Mar. 2009
  Yuichi Otsuka, Osaka University, Principal investigator
  The purpose of this research project is to verify that capping can occur in cytoplasm as well as nucleus, and show the significance of cytoplasmic capping in gene expression. I identified many target mRNAs to which cap structures would be added in cytoplasm. Also, deep sequencing analysis suggested that some of these mRNAs might have poly(U) tail at 3' terminus. These modifications on mRNA may play important roles in gene expression. In a different research project, I showed that bacteriophage T4 had an antitoxin against E.coli toxins for its own survival.
  Competitive research funding, Grant number：21870020
• Relationship of cytoplasmic capping to translation and mRNA decay　　　　　　　　　　　　　　　
  American Heart Association, Jul. 2006 - Jun. 2008
  Yuichi Otsuka, Principal investigator
  Competitive research funding

• サイエンスらいおんカフェ Vol.63 微生物カフェ 〜ウイルスと細菌の終わりなき戦い〜　　　　　　　　　　　　　　　
  lecturer
  03 Mar. 2018
• 栃木県立宇都宮女子高等学校SSH　　　　　　　　　　　　　　　
  lecturer, advisor
  Apr. 2017 - Mar. 2018
• 栃木県高等学校教育研究会理科部会 科学研究会　　　　　　　　　　　　　　　
  lecturer
  15 Nov. 2017
• 高校生のためのウイルス学体験講座　　　　　　　　　　　　　　　
  lecturer
  Aug. 2014 - Aug. 2017