PMID:11123679
| Citation |
Govantes, F, Orjalo, AV and Gunsalus, RP (2000) Interplay between three global regulatory proteins mediates oxygen regulation of the Escherichia coli cytochrome d oxidase (cydAB) operon. Mol. Microbiol. 38:1061-73 |
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| Abstract |
The Escherichia coli cydAB operon, encoding the subunits of the high-affinity cytochrome d oxidase, is maximally transcribed in microaerobiosis as a result of the combined action of the oxygen-responsive regulators Fnr and ArcA. Here, we report that the histone-like protein H-NS is an aerobic repressor of cydAB expression. ArcA is shown to antagonize H-NS action to render cydAB expression insensitive to H-NS repression in anaerobiosis. The targets for H-NS-mediated aerobic repression are the four oxygen-regulated promoters, designated P1, P2, P3 and P4. H-NS control is the result of H-NS binding to an extended region within the cydAB promoter element, including sequences upstream from and overlapping the four regulated promoters. We propose a regulatory model in which oxygen control of cydAB transcription is mediated by three alternative protein-DNA complexes that are assembled sequentially on the promoter region as the cells are shifted from aerobic to microaerobic and to anaerobic conditions. According to this model, ArcA-P plays a central role in cydAB regulation by antagonizing H-NS repression of cydAB transcription when oxygen becomes limiting. This allows peak gene expression and subsequent repression by Fnr under fully anaerobic conditions. |
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| Keywords |
Bacterial Proteins; Base Sequence; Cytochrome d Group/genetics; DNA Primers; DNA-Binding Proteins/physiology; Escherichia coli/enzymology; Operon; Oxygen/metabolism; Promoter Regions, Genetic; Transcription, Genetic/physiology |
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