5ond
From Proteopedia
RfaH from Escherichia coli in complex with ops DNA
Structural highlights
Function[RFAH_ECOLI] Enhances distal genes transcription elongation in a specialized subset of operons that encode extracytoplasmic components. RfaH is recruited into a multi-component RNA polymerase complex by the ops element, which is a short conserved DNA sequence located downstream of the main promoter of these operons. Once bound, RfaH suppresses pausing and inhibits Rho-dependent and intrinsic termination at a subset of sites. Termination signals are bypassed, which allows complete synthesis of long RNA chains. Enhances expression of several operons involved in synthesis of lipopolysaccharides, exopolysaccharides, hemolysin, and sex factor. Also negatively controls expression and surface presentation of AG43 and possibly another AG43-independent factor that mediates cell-cell interactions and biofilm formation.[1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedRfaH, a transcription regulator of the universally conserved NusG/Spt5 family, utilizes a unique mode of recruitment to elongating RNA polymerase to activate virulence genes. RfaH function depends critically on an ops sequence, an exemplar of a consensus pause, in the non-template DNA strand of the transcription bubble. We used structural and functional analyses to elucidate the role of ops in RfaH recruitment. Our results demonstrate that ops induces pausing to facilitate RfaH binding and establishes direct contacts with RfaH. Strikingly, the non-template DNA forms a hairpin in the RfaH:ops complex structure, flipping out a conserved T residue that is specifically recognized by RfaH. Molecular modeling and genetic evidence support the notion that ops hairpin is required for RfaH recruitment. We argue that both the sequence and the structure of the non-template strand are read out by transcription factors, expanding the repertoire of transcriptional regulators in all domains of life. The universally-conserved transcription factor RfaH is recruited to a hairpin structure of the non-template DNA strand.,Zuber PK, Artsimovitch I, NandyMazumdar M, Liu Z, Nedialkov Y, Schweimer K, Rosch P, Knauer SH Elife. 2018 May 9;7. pii: 36349. doi: 10.7554/eLife.36349. PMID:29741479[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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