Identification of the WhiB5 regulon in Mycobacterium tuberculosis H37Rv

ABSTRACT: We used DNA microarrays to define the M. tuberculosis whiB5 regulon and to study the variation of the global transcription profile in response of its induction. For this purpose we constructed a M. tuberculosis strain in which whiB5 was transcribed from an pristinamycin-inducible promoter and its transcriptional profile was compared on DNA microarray with the transcriptional profile of its control strain (empty vector-containing clone). WhiB5 induction for 15’ resulted in the induction of 26 genes, while induction for 3 h resulted in the induction of 58 genes. Interestingly, all of the 26 genes induced after 15 minutes of incubation with pristinamycin were still induced after 3 h of incubation. No repressed genes were identified. Among the induced genes we found the alternative sigma factor SigM and at least 12 genes previously shown to be regulated by this sigma factor, including those encoding the ESX-4 type VII secretion system. Interestingly, also the genes encoding ESX-2 type VII secretion system were strongly induced together with an operon probably involved in hydrogen metabolism in anaerobiosis. 10 representative genes were chosen from the microarray experiments and their expression was measured by quantitative RT-PCR using sigA as invariant internal control. In support to the gene expression profiling data, the mRNA levels of all selected genes was clearly higher in the whiB5 mutant strain relative to control. We compared the global gene expression of the whiB5 overexpressing strain and the control strain of Mtb in different conditions: after 15 min of induction or after 3 hours of induction. Hybridizations were performed using RNA extracted from three different biological samples. Each sample was hybridized twice through swap labeling of the respective cDNAs.

ORGANISM(S): Mycobacterium tuberculosis H37Rv

SUBMITTER: Stefano Casonato 

PROVIDER: E-GEOD-30299 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress