scholarly journals The Alternative Sigma Factor SigH Regulates Major Components of Oxidative and Heat Stress Responses in Mycobacterium tuberculosis

2001 ◽  
Vol 183 (20) ◽  
pp. 6119-6125 ◽  
Author(s):  
Sahadevan Raman ◽  
Taeksun Song ◽  
Xiaoling Puyang ◽  
Stoyan Bardarov ◽  
William R. Jacobs ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mycobacterium Tuberculosis ◽  
Heat Stress ◽  
Heat Shock ◽  
Stress Responses ◽  
Sigma Factor ◽  
Inducible Expression ◽  
Alternative Sigma Factor ◽  
And Oxidative Stress

ABSTRACT Mycobacterium tuberculosis is a specialized intracellular pathogen that must regulate gene expression to overcome stresses produced by host defenses during infection. SigH is an alternative sigma factor that we have previously shown plays a role in the response to stress of the saprophyte Mycobacterium smegmatis. In this work we investigated the role ofsigH in the M.tuberculosis response to heat and oxidative stress. We determined that a M. tuberculosis sigHmutant is more susceptible to oxidative stresses and that the inducible expression of the thioredoxin reductase/thioredoxin genestrxB2/trxC and a gene of unknown function, Rv2466c, is regulated by sigH via expression from promoters directly recognized by SigH. We also determined that thesigH mutant is more susceptible to heat stress and that inducible expression of the heat shock genes dnaK andclpB is positively regulated by sigH. The induction of these heat shock gene promoters but not of other SigH-dependent promoters was markedly greater in response to heat versus oxidative stress, consistent with their additional regulation by a heat-labile repressor. To further understand the role ofsigH in the M.tuberculosis stress response, we investigated the regulation of the stress-responsive sigma factor genessigE and sigB. We determined that inducible expression of sigE is regulated bysigH and that basal and inducible expression ofsigB is dependent on sigE andsigH. These data indicate that sigH plays a central role in a network that regulates heat and oxidative-stress responses that are likely to be important in M.tuberculosis pathogenesis.

scholarly journals Deletionof Mycobacterium tuberculosis Sigma Factor E Results inDelayed Time to Death with Bacterial Persistence in the Lungsof Aerosol-InfectedMice

2003 ◽  
Vol 71 (12) ◽  
pp. 7170-7172 ◽  
Author(s):  
Masaru Ando ◽  
Tetsuyuki Yoshimatsu ◽  
Chiew Ko ◽  
Paul J. Converse ◽  
William R. Bishai
Keyword(s):  
Oxidative Stress ◽  
Mycobacterium Tuberculosis ◽  
Heat Shock ◽  
Sodium Dodecyl Sulfate ◽  
Sigma Factor ◽  
Sodium Dodecyl ◽  
Bacterial Persistence ◽  
Time To Death ◽  
And Oxidative Stress ◽  
Sigma Factor E

ABSTRACT The stress-induced extracytoplasmic sigma factor E (SigE) of Mycobacterium tuberculosis shows increased expression after heat shock, sodium dodecyl sulfate treatment, and oxidative stress, as well as after phagocytosis in macrophages. We report that deletion of sigE results in delayed lethality in mice without a significant reduction of bacterial numbers in lungs.

The ECF sigma factor σTis involved in osmotic and oxidative stress responses in Caulobacter crescentus

2007 ◽  
Vol 66 (5) ◽  
pp. 1240-1255 ◽  
Author(s):  
Cristina E. Alvarez-Martinez ◽  
Rogério F. Lourenço ◽  
Regina L. Baldini ◽  
Michael T. Laub ◽  
Suely L. Gomes
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Sigma Factor ◽  
Caulobacter Crescentus ◽  
Ecf Sigma Factor ◽  
Oxidative Stress Responses ◽  
And Oxidative Stress

scholarly journals Heat Stress Activates Fission Yeast Spc1/StyI MAPK by a MEKK-Independent Mechanism

1998 ◽  
Vol 9 (6) ◽  
pp. 1339-1349 ◽  
Author(s):  
Kazuhiro Shiozaki ◽  
Mitsue Shiozaki ◽  
Paul Russell
Keyword(s):  
Oxidative Stress ◽  
Heat Stress ◽  
Heat Shock ◽  
Fission Yeast ◽  
Phosphorylation Sites ◽  
High Osmolarity ◽  
Mapk Kinase ◽  
Independent Mechanism ◽  
Heat Shock Responses ◽  
And Oxidative Stress

Fission yeast Spc1/StyI MAPK is activated by many environmental insults including high osmolarity, oxidative stress, and heat shock. Spc1/StyI is activated by Wis1, a MAPK kinase (MEK), which is itself activated by Wik1/Wak1/Wis4, a MEK kinase (MEKK). Spc1/StyI is inactivated by the tyrosine phosphatases Pyp1 and Pyp2. Inhibition of Pyp1 was recently reported to play a crucial role in the oxidative stress and heat shock responses. These conclusions were based on three findings: 1) osmotic, oxidative, and heat stresses activate Spc1/StyI in wis4 cells; 2) oxidative stress and heat shock activate Spc1/StyI in cells that express Wis1AA, in which MEKK consensus phosphorylation sites were replaced with alanine; and 3) Spc1/StyI is maximally activated in Δpyp1 cells. Contrary to these findings, we report: 1) Spc1/StyI activation by osmotic stress is greatly reduced in wis4 cells; 2)wis1-AA and Δwis1 cells have identical phenotypes; and 3) all forms of stress activate Spc1/StyI inΔpyp1 cells. We also report that heat shock, but not osmotic or oxidative stress, activate Spc1 in wis1-DDcells, which express Wis1 protein that has the MEKK consensus phosphorylation sites replaced with aspartic acid. Thus osmotic and oxidative stress activate Spc1/StyI by a MEKK-dependent process, whereas heat shock activates Spc1/StyI by a novel mechanism that does not require MEKK activation or Pyp1 inhibition.

scholarly journals AlgU Controls Expression of Virulence Genes in Pseudomonas syringae pv. tomato DC3000

2016 ◽  
Vol 198 (17) ◽  
pp. 2330-2344 ◽  
Author(s):  
Eric Markel ◽  
Paul Stodghill ◽  
Zhongmeng Bao ◽  
Christopher R. Myers ◽  
Bryan Swingle
Keyword(s):  
Oxidative Stress ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Sigma Factor ◽  
Pathogenic Bacteria ◽  
Promoter Sequence ◽  
Tomato Dc3000 ◽  
Content Type ◽  
Plant Pathogenic Bacteria ◽  
And Oxidative Stress

ABSTRACTPlant-pathogenic bacteria are able to integrate information about their environment and adjust gene expression to provide adaptive functions. AlgU, an extracytoplasmic function (ECF) sigma factor encoded byPseudomonas syringae, controls expression of genes for alginate biosynthesis and genes involved with resisting osmotic and oxidative stress. AlgU is active while these bacteria are associated with plants, where its presence supports bacterial growth and disease symptoms. We found that AlgU is an important virulence factor forP. syringaepv. tomato DC3000 but that alginate production is dispensable for disease in host plants. This implies that AlgU regulates additional genes that facilitate bacterial pathogenesis. We used transcriptome sequencing (RNA-seq) to characterize the AlgU regulon and chromatin immunoprecipitation sequencing (ChIP-seq) to identify AlgU-regulated promoters associated with genes directly controlled by this sigma factor. We found that in addition to genes involved with alginate and osmotic and oxidative stress responses, AlgU regulates genes with known virulence functions, including components of the Hrp type III secretion system, virulence effectors, and thehrpLandhrpRStranscription regulators. These data suggest thatP. syringaepv. tomato DC3000 has adapted to use signals that activate AlgU to induce expression of important virulence functions that facilitate survival and disease in plants.IMPORTANCEPlant immune systems produce antimicrobial and bacteriostatic conditions in response to bacterial infection. Plant-pathogenic bacteria are adapted to suppress and/or tolerate these conditions; however, the mechanisms controlling these bacterial systems are largely uncharacterized. The work presented here provides a mechanistic explanation for howP. syringaepv. tomato DC3000 coordinates expression of multiple genetic systems, including those dedicated to pathogenicity, in response to environmental conditions. This work demonstrates the scope of AlgU regulation inP. syringaepv. tomato DC3000 and characterizes the promoter sequence regulated by AlgU in these bacteria.

Sign in / Sign up

Export Citation Format

Share Document