title: tRNA-targeting ribonucleases: molecular mechanisms and insights into their physiological roles.
abstract: Most bacteria produce antibacterial proteins known as bacteriocins, which aid bacterial defence systems to provide a physiological advantage. To date, many kinds of bacteriocins have been characterized. Colicin has long been known as a plasmidborne bacteriocin that kills other Escherichia coli cells lacking the same plasmid. To defeat other cells, colicins exert specific activities such as ion-channel, DNase, and RNase activity. Colicin E5 and colicin D impair protein synthesis in sensitive E. coli cells; however, their physiological targets have not long been identified. This review describes our finding that colicins E5 and D are novel RNases targeting specific E. coli tRNAs and elucidates their enzymatic properties based on biochemical analyses and X-ray crystal structures. Moreover, tRNA cleavage mediates bacteriostasis, which depends on trans-translation. Based on these results and others, cell growth regulation depending on tRNA cleavage is also discussed.
authors.affiliation: a Department of Biotechnology , The University of Tokyo , Tokyo , Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000898:Antibiosis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; C501879:colicin D immunity protein, E coli; D012343:RNA, Transfer; D004722:Endoribonucleases; C515828:colicin E5 protein, E coli
keywords: cell competition; growth regulation; ribonuclease; tRNA