title: Functional characterization of RelBE toxin-antitoxin system in probiotic Bifidobacterium longum JDM301.
abstract: Toxin-antitoxin (TA) systems are widespread in bacteria and archaea. However, the roles of chromosomally encoded TA systems in bacterial physiology are still open to debate. In this study, a TA module-relBE in Bifidobacterium longum JDM301 (relBE(Bif)) was identified and its function in stress response was evaluated. Bioinformatics analysis of the whole genome sequences of JDM301 revealed a pair of linked genes encoding a RelBE-like TA system (RelBE(Bif)). Our results revealed a bicistronic operon formed by relBE(Bif) in JDM301. Over-expression of RelE(Bif) had a toxic effect on Escherichia coli, which could be neutralized by co-expression of its cognate antitoxin, RelB(Bif) Our data also demonstrated that RelE(Bif) is an mRNA interferase and that the activity of RelE(Bif) can be inhibited by RelB(Bif) These results suggest that RelE(Bif) is a toxic nuclease which arrests cell growth through mRNA degradation, and that the activity of RelE(Bif) can be abolished by co-expression of RelB(Bif) In addition, we also found that the expression of RelBE(Bif) is increased during osmotic stress, suggesting that RelBE(Bif) is activated under this adverse condition. Our results imply that the RelBE(Bif) TA module may represent a cell growth modulator which helps B. longum to deal with osmotic stress.
authors.affiliation: Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity/School of Stomatology, Xuzhou Medical University, Xuzhou 221004, China.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Microbiology and Immunity, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Ye
authors.affiliation: Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity/School of Stomatology, Xuzhou Medical University, Xuzhou 221004, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity/School of Stomatology, Xuzhou Medical University, Xuzhou 221004, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity/School of Stomatology, Xuzhou Medical University, Xuzhou 221004, China.
authors.forename: Dianbin
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Immunity, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity/School of Stomatology, Xuzhou Medical University, Xuzhou 221004, China tiantianlc@sjtu.edu.cn tangrenxian-t@163.com.
authors.forename: Renxian
authors.initials: R
authors.lastname: Tang
authors.affiliation: Department of Microbiology and Immunity, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China tiantianlc@sjtu.edu.cn tangrenxian-t@163.com.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
mesh_terms: D000992:Antitoxins / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000235:genetics / Q000494:pharmacology*; D000069978:Bifidobacterium longum / Q000378:metabolism*; D002876:Chromosomes, Bacterial; D009997:Osmotic Pressure; D010802:Phylogeny; D019936:Probiotics; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D000992:Antitoxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D012333:RNA, Messenger
keywords: Bifidobacterium longum; osmotic stress; toxin–antitoxin module; tufA