(P)ppGpp synthase Rsh promotes persister cells formation by regulating sulfur metabolism mediated by sulfate reductase CysI in Brucella abortus.

Persister cells constitute a subpopulation of dormant cells that are transiently tolerant to antibiotics and associated with chronic infection. We have known (p)ppGpp synthetase Rsh promoted persister cells formation during rifampicin exposure in Brucella, but the metabolic regulation mechanism by which Rsh promotes persister cells formation is unknown. In this study, we firstly characterized the proteome and metabolome of persister cells formation during rifampicin exposure between B. abortus A19 (WT) and Δrsh strains. We found that sulfur metabolism-related protein (NAD(P)/FAD-dependent sulfite reductase, cysI) was significantly down-regulated in Δrsh compared with WT strain during persister cells formation (P < 0.01). The Rsh significantly affected hydrogen sulfide consumption by hydrogen sulfide measurement (P < 0.01). And then we found Rsh positively regulated CysI that its promoter region was 122 bp of upstream of cysI gene. In addition, the cysI knockout strain (ΔcysI) was constructed which significantly reduced persister cells formation (P < 0.01) and also reduced consumption of hydrogen sulfide compared with WT strain. Taken together, we firstly reported that (p)ppGpp synthetase Rsh promotes persister cells formation through regulating sulfur metabolism mediated by sulfite reductase CysI in B. abortus. Our results provide a potential target and new strategy for clearing persister cells as well as prevention of Brucella infection.