title: RnlB Antitoxin of the Escherichia coli RnlA-RnlB Toxin-Antitoxin Module Requires RNase HI for Inhibition of RnlA Toxin Activity.
abstract: TheEscherichia coliRnlA-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 T4dmdencoding a phage antitoxin against RnlA is defective. Intriguingly,E. coliRNase 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.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. k.naka@bio.sci.osaka-u.ac.jp.
authors.forename: Kenta
authors.initials: K
authors.lastname: Naka
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. qidan@bio.sci.osaka-u.ac.jp.
authors.forename: Dan
authors.initials: D
authors.lastname: Qi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. yonesaki@bio.sci.osaka-u.ac.jp.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Yonesaki
authors.affiliation: Department of Microbiology, School of Medicine, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan. otsukay@dokkyomed.ac.jp.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Otsuka
mesh_terms: D017122:Bacteriophage T4 / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020871:RNA Stability; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D016914:Ribonuclease H / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C453723:Dmd protein, Enterobacteria phage T4; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; C525943:RnlA protein, E coli; D014764:Viral Proteins; C557568:rnlB protein, E coli; D016914:Ribonuclease H; C078856:ribonuclease HI
keywords: Escherichia coli; RNase HI; RnlA-RnlB; bacteriophage; toxin–antitoxin system