Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental cha...Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental challenges and trigger the SigB pathway. In Bacillus subtilis, two phosphorylation sites in RsbR are involved in activating the SigB pathway and a feedback mechanism, respectively. In this study, the role of RsbR in L. monocytogenes under mild and severe stresses was investigated. Strains with genetic deletion(Δrsb R), complementation(C-Δrsb R), and phosphorylation site mutations in the rsbR(RsbR-T175 A, RsbR-T209 A, and RsbR-T175 A-T209 A) were constructed to evaluate the roles of these RsbR sequences in listerial growth and survival. SigB was examined at the transcriptional and translational levels. Deletion of rsb R reduced listerial growxth and survival in response to acidic stress. Substitution of the phosphorylation residue RsbR-T175 A disabled RsbR complementation, while RsbR-T209 A significantly upregulated SigB expression and listerial survival. Our results provide clear evidence that two phosphorylation sites of Rsb R are functional in L. monocytogenes under acidic conditions, similar to the situation in B. subtilis.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.31702250 and 31600292)the Open Fund Project by Key Laboratory of Animal Preventive Medicine of Zhejiang Province(No.ZPKLPVM2017KFKT001),China
文摘Listeria monocytogenes is an important zoonotic foodborne pathogen that can tolerate a number of environmental stresses. Rsb R, an upstream regulator of the sigma B(Sig B) factor, is thought to sense environmental challenges and trigger the SigB pathway. In Bacillus subtilis, two phosphorylation sites in RsbR are involved in activating the SigB pathway and a feedback mechanism, respectively. In this study, the role of RsbR in L. monocytogenes under mild and severe stresses was investigated. Strains with genetic deletion(Δrsb R), complementation(C-Δrsb R), and phosphorylation site mutations in the rsbR(RsbR-T175 A, RsbR-T209 A, and RsbR-T175 A-T209 A) were constructed to evaluate the roles of these RsbR sequences in listerial growth and survival. SigB was examined at the transcriptional and translational levels. Deletion of rsb R reduced listerial growxth and survival in response to acidic stress. Substitution of the phosphorylation residue RsbR-T175 A disabled RsbR complementation, while RsbR-T209 A significantly upregulated SigB expression and listerial survival. Our results provide clear evidence that two phosphorylation sites of Rsb R are functional in L. monocytogenes under acidic conditions, similar to the situation in B. subtilis.
