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The −35 sequence location and the Fis–sigma factor interface determine σ S selectivity of the proP (P2) promoter in Escherichia coli
Author(s) -
Typas Athanasios,
Stella Stefano,
Johnson Reid C.,
Hengge Regine
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05560.x
Subject(s) - sigma factor , rpos , sigma , rna polymerase , biology , promoter , activator (genetics) , transcription (linguistics) , random hexamer , gene , genetics , escherichia coli , microbiology and biotechnology , physics , gene expression , linguistics , philosophy , quantum mechanics
Summary The P2 promoter of proP , encoding a transporter for proline and glycine betaine in Escherichia coli , is a unique paradigm, where master regulators of different growth stages, Fis and σ S (RpoS), collaborate to achieve promoter activation. It is also the only case described where Fis functions as class II transcriptional activator (centred at −41). Here we show that the degenerate −35 sequence, and the location of the Fis binding site, which forces a suboptimal 16 bp spacing between the −35 and −10 elements, allow only σ S but not σ 70 to function at proP (P2). Moreover, the interface between Fis and σ S seems better suited to σ S , due to a single residue difference between σ S and σ 70 . Nevertheless, Fis can activate RNA polymerase containing σ 70 at a proP (P2) promoter variant, in which a typical σ 70 −35 recognition sequence has been introduced at a 17 bp distance from the −10 hexamer. In summary, we elucidate the rules that govern sigma factor selectivity in the presence of a class II activator, provide new insight into transcriptional activation by Fis from this position, and clarify, why the proP (P2) promoter is precisely activated during a short time window of the growth cycle, when Fis and σ S are both present.