2h27
From Proteopedia
Crystal Structure of Escherichia coli SigmaE Region 4 Bound to its-35 Element DNA
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] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe control of bacterial transcription initiation depends on a primary sigma factor for housekeeping functions, as well as alternative sigma factors that control regulons in response to environmental stresses. The largest and most diverse subgroup of alternative sigma factors, the group IV extracytoplasmic function sigma factors, directs the transcription of genes that regulate a wide variety of responses, including envelope stress and pathogenesis. We determined the 2.3-A resolution crystal structure of the -35 element recognition domain of a group IV sigma factor, Escherichia coli sigma(E)4, bound to its consensus -35 element, GGAACTT. Despite similar function and secondary structure, the primary and group IV sigma factors recognize their -35 elements using distinct mechanisms. Conserved sequence elements of the sigma(E) -35 element induce a DNA geometry characteristic of AA/TT-tract DNA, including a rigid, straight double-helical axis and a narrow minor groove. For this reason, the highly conserved AA in the middle of the GGAACTT motif is essential for -35 element recognition by sigma(E)4, despite the absence of direct protein-DNA interactions with these DNA bases. These principles of sigma(E)4/-35 element recognition can be applied to a wide range of other group IV sigma factors. The structural basis for promoter -35 element recognition by the group IV sigma factors.,Lane WJ, Darst SA PLoS Biol. 2006 Sep;4(9):e269. PMID:16903784[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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