Dataset Information

Regulation of perR expression by iron and PerR in Campylobacter jejuni.

ABSTRACT: Campylobacter jejuni is a leading food-borne pathogen causing gastroenteritis in humans. Although OxyR is a widespread oxidative stress regulator in many Gram-negative bacteria, C. jejuni lacks OxyR and instead possesses the metalloregulator PerR. Despite the important role played by PerR in oxidative stress defense, little is known about the factors influencing perR expression in C. jejuni. In this study, a perR promoter-lacZ fusion assay demonstrated that iron significantly reduced the level of perR transcription, whereas other metal ions, such as copper, cobalt, manganese, and zinc, did not affect perR transcription. Notably, a perR mutation substantially increased the level of perR transcription and in trans complementation restored the transcriptional changes, suggesting perR is transcriptionally autoregulated in C. jejuni. In the perR mutant, iron did not repress perR transcription, indicating the iron dependence of perR expression results from perR autoregulation. Electrophoretic mobility shift assays showed that PerR binds to the perR promoter, and DNase I footprinting assays identified a PerR binding site overlapping the -35 region of the two perR promoters, further supporting perR autoregulation at the transcriptional level. Alignment of the PerR binding sequence in the perR promoter with the regulatory region of other PerR regulon genes of C. jejuni revealed a 16-bp consensus PerR binding sequence, which shares high similarities to the Bacillus subtilis PerR box. The results of this study demonstrated that PerR directly interacts with the perR promoter and regulates perR transcription and that perR autoregulation is responsible for the repression of perR transcription by iron in C. jejuni.

SUBMITTER: Kim M

PROVIDER: S-EPMC3209207 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Regulation of perR expression by iron and PerR in Campylobacter jejuni.

Kim Minkyeong M Hwang Sunyoung S Ryu Sangryeol S Jeon Byeonghwa B

Journal of bacteriology 20110909 22

Campylobacter jejuni is a leading food-borne pathogen causing gastroenteritis in humans. Although OxyR is a widespread oxidative stress regulator in many Gram-negative bacteria, C. jejuni lacks OxyR and instead possesses the metalloregulator PerR. Despite the important role played by PerR in oxidative stress defense, little is known about the factors influencing perR expression in C. jejuni. In this study, a perR promoter-lacZ fusion assay demonstrated that iron significantly reduced the level o ...[more]

PMID: 21908670

Similar Datasets

Project description:The genome of Campylobacter jejuni contains two iron activated Fur-family transcriptional regulators, CjFur and CjPerR, which are primarily responsible for regulating iron homeostasis and oxidative stress respectively. Both transcriptional regulators have been previously implicated in regulating diverse functions beyond their primary roles in C. jejuni. To further characterize their regulatory networks, RNA-seq was used to define the transcriptional profiles of C. jejuni NCTC11168 wild type, ?fur, ?perR and ?fur?perR isogenic deletion mutants under both iron-replete and iron-limited conditions.It was found that 202 genes were differentially expressed in at least one mutant under iron-replete conditions and 331 genes were differentially expressed in at least one mutant under iron-limited conditions. The CjFur and CjPerR transcriptomes characterized in this study were compared to those previously identified using microarray profiling and found to be more extensive than previously understood. Interestingly, our results indicate that CjFur/CjPerR appear to co-regulate the expression of flagellar biogenesis genes in an opposing and iron-independent fashion. Moreover the ?fur?perR isogenic deletion mutant revealed that CjFur and CjPerR can compensate for each other in certain cases, suggesting that both regulators may compete for binding to specific promoters.The CjFur and CjPerR transcriptomes are larger than previously reported. In particular, deletion of perR results in the differential expression of a large group of genes in the absence of iron, suggesting that CjPerR may also regulate genes in an iron-independent manner, similar to what has already been demonstrated with CjFur. Moreover, subsets of genes were found which are only differentially expressed when both CjFur and CjPerR are deleted and includes genes that appear to be simultaneously activated by CjFur and repressed by CjPerR. In particular the iron-independent co-regulation of flagellar biogenesis by CjFur/CjPerR represents a potentially novel regulatory function for these proteins. These findings represent additional modes of co-regulation by these two transcriptional regulators in C. jejuni.

Project description:The expression of iron-regulated systems in gram-negative bacteria is generally controlled by the Fur protein, which represses the transcription of iron-regulated promoters by using Fe2+ as a cofactor. Mutational analysis of the Campylobacter jejuni fur gene was carried out by generation of a set of mutant copies of fur which had a kanamycin or chloramphenicol resistance gene introduced into the regions encoding the N and C termini of the Fur protein. The mutated genes were recombined into the C. jejuni NCTC 11168 chromosome, and putative mutants were confirmed by Southern hybridization. C. jejuni mutants were obtained only when the resistance genes were transcribed in the same orientation as the fur gene. The C. jejuni fur mutant grew slower than the parental strain. Comparison of protein profiles of fractionated C. jejuni cells grown in low- or high-iron medium indicated derepressed expression of three iron-regulated outer membrane proteins with molecular masses of 70, 75, and 80 kDa. Characterization by N-terminal amino acid sequencing showed the 75-kDa protein to be identical to CfrA, a Campylobacter coli siderophore receptor homologue, whereas the 70-kDa protein was identified as a new siderophore receptor homologue. Periplasmic fractions contained four derepressed proteins with molecular masses of 19, 29, 32, and 36 kDa. The 19-kDa protein has been previously identified, but its function is unknown. The cytoplasmic fraction contained two iron-repressed and two iron-induced proteins with molecular masses of 26, 55, 31, and 40 kDa, respectively. The two iron-repressed proteins have been previously identified as the oxidative stress defense proteins catalase (KatA) and alkyl hydroperoxide reductase (AhpC). AhpC and KatA were still iron regulated in the fur mutant, suggesting the presence of Fur-independent iron regulation. Further analysis of the C. jejuni iron and Fur regulons by using two-dimensional gel electrophoresis demonstrated the total number of iron- and Fur-regulated proteins to be lower than for other bacterial pathogens.

Dataset Information

Regulation of perR expression by iron and PerR in Campylobacter jejuni.

Publications

Regulation of perR expression by iron and PerR in Campylobacter jejuni.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets