Transcriptional Regulation And Function Of Dps In Stress Resistance In Vibrio Cholerae

Cholera is an old and prevalent sweepingly acute intestinal disease,with symptoms of acute secretory diarrhea and dehydration.People may die of it.Cholera is still a major theat to public health in developing countries.The causative agent of cholera is the gram-negative,single flagellum,motile pathogenic bacterium with arc-shaped pathogen bacteria:vibrio cholerae,which usually survives in aquatic environment.People get infected by eating contaminated food or water,after getting through human gastrointestinal tract,V.cholerae get through the mucus in the small intestine and begin to colonize.Within a human host,V.cholerae senses stresses signals,and is able to modulare its gene expression in order to combat these stresses,including the stress posed by reactive oxygen species(ROS).In order to further the understanding of V.cholerae's transcriptional response to ROS,we performed an RNA sequencinguencing analysis to determine the transcriptional profile of V.cholerae when exposed to hydrogen hydroperoxide.Of 135 differentially expressed genes,VC0139 was amongst the genes with the largest induction.VC0139 encodes a protein homologous to the Dps(DNA-binding protein from starved cells)protein family,which are widely conserved and are implicated in ROS resistance in other bacteria.Using a promoter reporter assay,we show that during exponential growth,dps is induced by H2O2 in a manner dependent on the ROS-sensing transcriptional regulator,OxyR.Upon entry into stationary phase,the major stationary phase regulator RpoS is required to transcribe dps.Deletion of dps impaired V.cholerae resistance to both inorganic and organic hydroperoxides.Furthermore,we show that Dps is involved both in resistance to multiple environmental stresses,such as high concentrations of ion,and the survival of V.cholerae in VBNC state.To investigate whether Dps plays a role in V.cholerae pathogenesis,we conducted competition colonization assay in both infant mice model and adult mice model and examined the expression and production of tcpA.Results show that in vitro tcpA induction and TcpA production were similar between wild type and Adps,suggesting that Dps does not affect virulence gene expression.?dps was outcompeted by wild type by 10 fold in adult mice model.However,treatment with N-acetyl cysteine(NAC),an antioxidant widely used in human and animal studies to lower ROS levels,restores ?dps colonization.These results suggest that Dps is important for ROS resistance in vivo.Taken together,our results suggest that Dps plays vital roles in both V.cholerae stress resistance and pathogenesis.As Dps is well conserved in many bacteria,including pathogens,our study contributes to the knowledge of pathogenic mechanisms required to achieve successful infection.