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The Mycobacterium tuberculosis ECF sigma factor σ E : role in global gene expression and survival in macrophages †
Author(s) -
Manganelli Riccardo,
Voskuil Martin I.,
Schoolnik Gary K.,
Smith Issar
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02525.x
Subject(s) - biology , sigma factor , regulon , mycobacterium tuberculosis , heat shock protein , gene , heat shock , mutant , gene expression , microbiology and biotechnology , microarray analysis techniques , virulence , promoter , genetics , tuberculosis , pathology , medicine
In previously published work, we identified three Mycobacterium tuberculosis sigma (σ) factor genes responding to heat shock ( sigB , sigE and sigH ). Two of them ( sigB and sigE ) also responded to SDS exposure. As these responses to stress suggested that the σ factors encoded by these genes could be involved in pathogenicity, we are studying their role in physiology and virulence. In this work, we characterize a sigE mutant of M. tuberculosis H37Rv. The sigE mutant strain was more sensitive than the wild‐type strain to heat shock, SDS and various oxidative stresses. It was also defective in the ability to grow inside both human and murine unactivated macrophages and was more sensitive than the wild‐type strain to the killing activity of activated murine macrophages. Using microarray technology and quantitative reverse transcription–polymerase chain reaction (RT–PCR), we started to define the σ E regulon of M. tuberculosis and its involvement in the global regulation of the stress induced by SDS. We showed the requirement for a functional sigE gene for full expression of sigB and for its induction after SDS exposure but not after heat shock. We also identified several genes that are no longer induced when σ E is absent. These genes encode proteins belonging to different classes including transcriptional regulators, enzymes involved in fatty acid degradation and classical heat shock proteins.