Requirement of Fur for the full induction of Dps expression in Salmonella enterica serovar typhimurium.
The Dps protein, which is overexpressed in harsh environments, is known to play a critical role in the protection of DNA against oxidative stresses. In this study, the roles of Fur in the expression of the dps gene in Salmonella and the protection mechanisms against oxidative stress in Salmonella cells preexposed to iron-stress were investigated. Two putative Fur boxes were predicted within the promoter region o f th e S. typhimurium dps gene . The profile of dps expression performed by the LacZ reporter assay revealed growth-phase dependency regardless of iron-status under the culture conditions. Thefur mutant, chi4659, evidenced a reduced level of beta-galactosidase as compared to the wild-type strain. The results observed after the measurement of the Dps protein in various Salmonella regulatory mutants were consistent with the results acquired in the reporter assay. This evidence suggested that Fur performs a function as a subsidiary regulator in the expression of dps. The survival ability of Salmonella strains after exposure to oxidative stress demonstrated that the Dps protein performs a pivotal function in the survival of stationary-phase S. typhimurium against oxidative stress. Salmonella cells grown in iron-restricted condition required Dps for full protection against oxidative stress. The CK24 (Deltadps) cells grown in iron-replete condition survived at a rate similar to that observed in the wild-type strain, thereby suggesting the induction of an unknown protection mechanism(s) other than Dps in this condition.
Division of Biological Sciences, Pusan National University, Busan 609-735, Korea.
Ah Young
AY
Yoo
Sam Woong
SW
Kim
Jong Earn
JE
Yu
Young Hee
YH
Kim
Jaeho
J
Cha
Jeong-Il
JI
Oh
Seong Kug
SK
Eo
John Hwa
JH
Lee
Ho Young
HY
Kang
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism / Q000494:pharmacology*; D018384:Oxidative Stress; D012097:Repressor Proteins / Q000502:physiology*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C083911:DPS protein, Bacteria; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron