5xe7
Crystal structure of Mycobacterium tuberculosis extracytoplasmic function sigma factor SigJ
Structural highlights
FunctionSIGJ_MYCTU Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. Extracytoplasmic function (ECF) sigma factors are held in an inactive form by an anti-sigma factor until released, although no anti-sigma factor is known for this protein (By similarity). Regulates the promoter of SigI, may not be autoregulated.[1] [2] Publication Abstract from PubMedExtra-cytoplasmic function (ECF) sigma-factors are widespread in bacteria, linking environmental stimuli with changes in gene expression. These transcription factors span several phylogenetically distinct groups and are remarkably diverse in their activation and regulatory mechanisms. Here, we describe the structural and biochemical features of a Mycobacterium tuberculosis ECF factor sigmaJ that suggests that the SnoaL_2 domain at the C-terminus can modulate the activity of this initiation factor in the absence of a cognate regulatory anti-sigma factor. M. tuberculosis sigmaJ can bind promoter DNA in vitro; this interaction is substantially impaired by the removal of the SnoaL_2 domain. This finding is consistent with assays to evaluate sigmaJ-mediated gene expression. Structural similarity of the SnoaL_2 domain with epoxide hydrolases also suggests a novel functional role for this domain. The conserved sequence features between M. tuberculosis sigmaJ and other members of the ECF41 family of sigma-factors suggest that the regulatory mechanism involving the C-terminal SnoaL_2 domain is likely to be retained in this family of proteins. These studies suggest that the ECF41 family of sigma-factors incorporate features of both-the sigma70 family and bacterial one-component systems thereby providing a direct mechanism to implement environment-mediated transcription changes. The fused SnoaL_2 domain in the Mycobacterium tuberculosis sigma factor sigmaJ modulates promoter recognition.,Goutam K, Gupta AK, Gopal B Nucleic Acids Res. 2017 Sep 19;45(16):9760-9772. doi: 10.1093/nar/gkx609. PMID:28934483[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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