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Mycobacterium tuberculosis origin of replication and the promoter for immunodominant secreted antigen 85B are the targets of MtrA, the essential response regulator.

ABSTRACT: Efficient proliferation of Mycobacterium tuberculosis (Mtb) inside macrophage requires that the essential response regulator MtrA be optimally phosphorylated. However, the genomic targets of MtrA have not been identified. We show by chromatin immunoprecipitation and DNase I footprinting that the chromosomal origin of replication, oriC, and the promoter for the major secreted immunodominant antigen Ag85B, encoded by fbpB, are MtrA targets. DNase I footprinting analysis revealed that MtrA recognizes two direct repeats of GTCACAgcg-like sequences and that MtrA approximately P, the phosphorylated form of MtrA, binds preferentially to these targets. The oriC contains several MtrA motifs, and replacement of all motifs or of a single select motif with TATATA compromises the ability of oriC plasmids to maintain stable autonomous replication in wild type and MtrA-overproducing strains, indicating that the integrity of the MtrA motif is necessary for oriC replication. The expression of the fbpB gene is found to be down-regulated in Mtb cells upon infection when these cells overproduce wild type MtrA but not when they overproduce a nonphosphorylated MtrA, indicating that MtrA approximately P regulates fbpB expression. We propose that MtrA is a regulator of oriC replication and that the ability of MtrA to affect apparently unrelated targets, i.e. oriC and fbpB, reflects its main role as a coordinator between the proliferative and pathogenic functions of Mtb.

SUBMITTER: Rajagopalan M

PROVIDER: S-EPMC2871449 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Mycobacterium tuberculosis origin of replication and the promoter for immunodominant secreted antigen 85B are the targets of MtrA, the essential response regulator.

Rajagopalan Malini M Dziedzic Renata R Al Zayer Maha M Stankowska Dorota D Ouimet Marie-Claude MC Bastedo D Patrick DP Marczynski Gregory T GT Madiraju Murty V MV

The Journal of biological chemistry 20100311 21

Efficient proliferation of Mycobacterium tuberculosis (Mtb) inside macrophage requires that the essential response regulator MtrA be optimally phosphorylated. However, the genomic targets of MtrA have not been identified. We show by chromatin immunoprecipitation and DNase I footprinting that the chromosomal origin of replication, oriC, and the promoter for the major secreted immunodominant antigen Ag85B, encoded by fbpB, are MtrA targets. DNase I footprinting analysis revealed that MtrA recogniz ...[more]

PMID: 20223818

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Project description:The Mycobacterium tuberculosis protein kinase K regulates growth adaptation by facilitating mycobacterial survival in response to a variety of in vitro and in vivo stress conditions. Here, we further add that pknK transcription is responsive to carbon and nitrogen starvation signals. The increased survival of an M. tuberculosis ΔpknK mutant strain under carbon- and nitrogen-limiting growth conditions compared to the wild-type (WT) H37Rv suggests an integral role of PknK in regulating growth during metabolic stress. To identify the downstream targets of PknK-mediated signaling, we compared phosphoproteomic and transcription profiles of mycobacterial strains overexpressing WT and phosphorylation-defective PknK. Results implicate PknK as a signaling protein that can regulate several enzymes involved in central metabolism, transcription regulation, and signal transduction. A key finding of this study was the identification of two essential two-component response regulator (RR) proteins, PrrA and MtrA, and Rho transcription terminator, as unique targets for PknK. We confirm that PknK interacts with and phosphorylates PrrA, MtrA, and Rho in vivo. PknK-mediated phosphorylation of MtrA appears to increase binding of the RR to the cognate probe DNA. However, dual phosphorylation of MtrA and PrrA response regulators by PknK and their respective cognate sensor kinases in vitro showed nominal additive effect on the mobility of the protein-DNA complex, suggesting the presence of a potential fine-tuning of the signal transduction pathway which might respond to multiple cues. IMPORTANCE Networks of gene regulation and signaling cascades are fundamental to the pathogenesis of Mycobacterium tuberculosis in adapting to the continuously changing intracellular environment in the host. M. tuberculosis protein kinase K is a transcription regulator that responds to diverse environmental signals and facilitates stress-induced growth adaptation in culture and during infection. This study identifies multiple signaling interactions of PknK and provides evidence that PknK can change the transcriptional landscape during growth transitions by connecting distinctly different signal transduction and regulatory pathways essential for mycobacterial survival.

Dataset Information

Mycobacterium tuberculosis origin of replication and the promoter for immunodominant secreted antigen 85B are the targets of MtrA, the essential response regulator.

Publications

Mycobacterium tuberculosis origin of replication and the promoter for immunodominant secreted antigen 85B are the targets of MtrA, the essential response regulator.

Similar Datasets

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