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An anti‐repression Fur operator upstream of the promoter is required for iron‐mediated transcriptional autoregulation in Helicobacter pylori
Author(s) -
Delany Isabel,
Spohn Gunther,
Rappuoli Rino,
Scarlato Vincenzo
Publication year - 2003
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 - 10.1046/j.1365-2958.2003.03757.x
Subject(s) - biology , psychological repression , transcription (linguistics) , promoter , repressor , transcription factor , operator (biology) , regulator , microbiology and biotechnology , gene , genetics , gene expression , philosophy , linguistics
Summary The Fur protein acts as a regulator of iron‐dependent gene transcription in bacteria. In Helicobacter pylori , Fur regulates iron‐activated and iron‐repressed promoters. It also acts as an autoregulatory rheostat of transcription to fine‐tune its own expression in response to iron by binding to three operators at its own promoter P fur . Using biochemical and genetic analyses, here we show that the distal upstream operator III (centred at −110) is essential for iron regulation of P fur and functions as an anti‐repression site that is bound by the iron‐free form of Fur to induce transcription. Furthermore, operator I (centred at −50) may have a dual role both as a high‐affinity binding site for Fur and as an UP element. We propose that its role is ensuring that Fur expression is not repressed below a minimum threshold level. Our data supports a novel promoter architecture and mechanism of regulation by Fur.