Regulation of Escherichia coli hemolysin E expression by H-NS and Salmonella SlyA.
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.
The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
Neil R
NR
Wyborn
Melanie R
MR
Stapleton
Valia A
VA
Norte
Ruth E
RE
Roberts
Jamie
J
Grafton
Jeffrey
J
Green
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D003470:Culture Media; D002373:Cyclic AMP Receptor Protein; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012475:Salmonella / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003470:Culture Media; D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; C031908:H-NS protein, bacteria; D006460:Hemolysin Proteins; D007506:Iron-Sulfur Proteins; D011956:Receptors, Cell Surface; D014157:Transcription Factors; C481662:crp protein, E coli; C119944:hlyE protein, E coli; C056785:salmolysin