5or5
From Proteopedia
NMR structure of the complex formed by an engineered region 2 of sigmaE in complex with GTAAAA
Structural highlights
Function[RPOE_ECOLI] Sigma factors are initiation factors that promote the attachment of RNA polymerase (RNAP) to specific initiation sites and are then released. Extracytoplasmic function (ECF) sigma-E controls the envelope stress response, responding to periplasmic protein stress, increased levels of periplasmic lipopolysaccharide (LPS) as well as heat shock and oxidative stress; it controls protein processing in the extracytoplasmic compartment. The 90 member regulon consists of the genes necessary for the synthesis and maintenance of both proteins and LPS of the outer membrane.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedBacterial transcription is controlled by sigma factors, the RNA polymerase subunits that act as initiation factors. Although a single housekeeping sigma factor enables transcription from thousands of promoters, environmentally induced sigma factors redirect gene expression toward small regulons to carry out focused responses. Using structural and functional analyses, we determined the molecular basis of -10 promoter element recognition by Escherichia coli sigmaE, which revealed an unprecedented way to achieve promoter melting. Group IV sigma factors induced strand separation at the -10 element by flipping out a single nucleotide from the nontemplate-strand DNA base stack. Unambiguous selection of this critical base was driven by a dynamic protein loop, which can be substituted to modify specificity of promoter recognition. This mechanism of promoter melting explains the increased promoter-selection stringency of environmentally induced sigma factors. Structural basis for -10 promoter element melting by environmentally induced sigma factors.,Campagne S, Marsh ME, Capitani G, Vorholt JA, Allain FH Nat Struct Mol Biol. 2014 Feb 16. doi: 10.1038/nsmb.2777. PMID:24531660[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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