PMID:9233812

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Citation

Barne, KA, Bown, JA, Busby, SJ and Minchin, SD (1997) Region 2.5 of the Escherichia coli RNA polymerase sigma70 subunit is responsible for the recognition of the 'extended-10' motif at promoters. EMBO J. 16:4034-40

Abstract

At some bacterial promoters, a 5'-TG-3' sequence element, located one base upstream of the -10 hexamer element, provides an essential motif necessary for transcription initiation. We have identified a mutant of the Escherichia coli RNA polymerase sigma70 subunit that has an altered preference for base sequences in this 'extended -10' region. We show that this mutant sigma70 subunit substantially increases transcription from promoters bearing 5'-TC-3' or 5'-TT-3' instead of a 5'-TG-3' motif, located one base upstream of the -10 hexamer. The mutant results from a single base pair substitution in the rpoD gene that causes a Glu to Gly change at position 458 of sigma70. This substitution identifies a functional region in sigma70 that is immediately adjacent to the well-characterized region 2.4 (positions 434-453, previously shown to contact the -10 hexamer). From these results, we conclude that this region (which we name region 2.5) is involved in contacting the 5'-TG-3' motif found at some bacterial promoters: thus, extended -10 regions are recognized by an extended region 2 of the RNA polymerase sigma70 subunit.

Links

PubMed PMC1170026 Online version:10.1093/emboj/16.13.4034

Keywords

Amino Acid Sequence; Base Sequence; Binding Sites; Conserved Sequence; DNA, Bacterial/metabolism; DNA-Directed RNA Polymerases/genetics; DNA-Directed RNA Polymerases/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Promoter Regions, Genetic; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Sigma Factor/genetics; Sigma Factor/metabolism

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