The Mycobacterium Tuberculosis ECF Sigma Factor sigmaE: Role in Global Gene Expression and Survival in Macrophages

Mol Microbiol. 2001 Jul;41(2):423-37. doi: 10.1046/j.1365-2958.2001.02525.x.


In previously published work, we identified three Mycobacterium tuberculosis sigma (sigma) 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 sigma 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 sigmaE 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 sigmaE is absent. These genes encode proteins belonging to different classes including transcriptional regulators, enzymes involved in fatty acid degradation and classical heat shock proteins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Cell Line
  • Consensus Sequence / genetics
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial* / drug effects
  • Genetic Complementation Test
  • Heat-Shock Proteins / genetics
  • Heat-Shock Response / genetics
  • Hot Temperature
  • Humans
  • Macrophages / immunology
  • Macrophages / microbiology*
  • Mice
  • Mutation
  • Mycobacterium tuberculosis / genetics*
  • Mycobacterium tuberculosis / growth & development
  • Mycobacterium tuberculosis / physiology*
  • Oligonucleotide Array Sequence Analysis
  • Oxidative Stress
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Regulon / genetics
  • Sigma Factor / genetics
  • Sigma Factor / metabolism*
  • Sodium Dodecyl Sulfate / pharmacology


  • Bacterial Proteins
  • Heat-Shock Proteins
  • RNA, Messenger
  • SigB protein, Bacteria
  • SigH protein, bacteria
  • Sigma Factor
  • sigE protein, Bacteria
  • Sodium Dodecyl Sulfate