PMID:14996792

Citation	Wyborn, NR, Stapleton, MR, Norte, VA, Roberts, RE, Grafton, J and Green, J (2004) Regulation of Escherichia coli hemolysin E expression by H-NS and Salmonella SlyA. J. Bacteriol. 186:1620-8
Abstract	The Escherichia coli hlyE gene (also known as clyA or sheA) codes for a novel pore-forming toxin. Previous work has shown that the global transcription factors FNR and CRP positively regulate hlyE expression by binding at the same site. Here in vivo transcription studies reveal that FNR occupies the hlyE promoter more frequently than CRP, providing a mechanism for the moderate upregulation of hlyE expression in response to two distinct environmental signals (oxygen and glucose starvation). It has been reported that H-NS interacts with two large regions of the hlyE promoter (PhlyE), one upstream of the -35 element and one downstream of the -10 element. Here we identify two high-affinity H-NS sites, H-NS I, located at the 3' end of the extended upstream footprint, and H-NS II, located at the 5' end of the extended downstream footprint. It is suggested that these high-affinity sites initiate the progressive formation of higher order complexes, allowing a range of H-NS-mediated regulatory effects at PhlyE. Finally, the identification of a SlyA binding site that overlaps the H-NS I site in PhlyE suggests a mechanism to explain how SlyA overproduction enhances hlyE expression by antagonizing the negative effects of H-NS.
Links	PubMed PMC355951
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacterial Toxins/genetics; Bacterial Toxins/metabolism; Binding Sites; Culture Media; Cyclic AMP Receptor Protein; DNA Footprinting; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Hemolysin Proteins/genetics; Hemolysin Proteins/metabolism; Iron-Sulfur Proteins/metabolism; Receptors, Cell Surface/metabolism; Salmonella/metabolism; Transcription Factors
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECO57:HLYE		GO:0019836: hemolysis by symbiont of host erythrocytes	ECO:0000314:		P		Fig 2: FNR and CRP make positive contributions, whereas H-NS acts negatively under these conditions.	complete CACAO 10724

References

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