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| Content Provider | PubMed Central |
|---|---|
| Author | Bibb, Lori A. Kunkle, Carey A. Schmitt, Michael P. |
| Copyright Year | 2007 |
| Abstract | Transcription of the Corynebacterium diphtheriae hmuO gene, which encodes a heme oxygenase involved in heme iron utilization, is activated in a heme- or hemoglobin-dependent manner in part by the two-component system ChrA-ChrS. Mutation of either the chrA or the chrS gene resulted in a marked reduction of hemoglobin-dependent activation at the hmuO promoter in C. diphtheriae; however, it was observed that significant levels of hemoglobin-dependent expression were maintained in the mutants, suggesting that an additional activator is involved in regulation. A BLAST search of the C. diphtheriae genome sequence revealed a second two-component system, encoded by DIP2268 and DIP2267, that shares similarity with ChrS and ChrA, respectively; we have designated these genes hrrS (DIP2268) and hrrA (DIP2267). Analysis of hmuO promoter expression demonstrated that hemoglobin-dependent activity was fully abolished in strains from which both the chrA-chrS and the hrrA-hrrS two-component systems were deleted. Similarly, deletion of the sensor kinase genes chrS and hrrS or the genes encoding both of the response regulators chrA and hrrA also eliminated hemoglobin-dependent activation at the hmuO promoter. We also show that the regulators ChrA-ChrS and HrrA-HrrS are involved in the hemoglobin-dependent repression of the promoter upstream of hemA, which encodes a heme biosynthesis enzyme. Evidence for cross talk between the ChrA-ChrS and HrrA-HrrS systems is presented. In conclusion, these findings demonstrate that the ChrA-ChrS and HrrA-HrrS regulatory systems are critical for full hemoglobin-dependent activation at the hmuO promoter and also suggest that these two-component systems are involved in the complex mechanism of the regulation of heme homeostasis in C. diphtheriae. |
| Related Links | http://dx.doi.org/10.1128/iai.01821-06 |
| Ending Page | 2431 |
| Page Count | 11 |
| Starting Page | 2421 |
| File Format | |
| ISSN | 00199567 |
| e-ISSN | 10985522 |
| Journal | Infection and Immunity |
| Issue Number | 5 |
| Volume Number | 75 |
| Language | English |
| Publisher | American Society for Microbiology |
| Publisher Date | 2007-05-01 |
| Access Restriction | Open |
| Rights Holder | American Society for Microbiology |
| Subject Keyword | Immunology Microbiology Parasitology Infectious Diseases Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Infectious Diseases Parasitology Immunology Microbiology |
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