Regulation of the Shiga-like toxin II operon in Escherichia coli.
Investigations of the regulation of the bacteriophage-encoded Shiga-like toxin II (SLT-II) in Escherichia coli demonstrated that bacteriophages exhibit a regulatory impact on toxin production by two mechanisms. Firstly, replication of the toxin-converting bacteriophages brings about an increase in toxin production due to concomitant multiplication of toxin gene copies. Secondly, an influence of a phage-encoded regulatory molecule was demonstrated by using low-copy-number plasmid pADR-28, carrying a translational gene fusion between the promoter and proximal portion of slt-IIA and the structural gene for bacterial alkaline phosphatase (phoA). PhoA activity, reflecting the slt-II promoter activity, was significantly enhanced in E. coli strains which and been lysogenized with an SLT-I or SLT-II-converting bacteriophage (H-19B or 933W, respectively) or bacteriophage lambda. Both mechanisms are dependent on bacteriophage induction and hence are recA dependent. Moreover, the study revealed that the DNA-binding protein H-NS has a regulatory impact on both bacteriophage-mediated SLT-II synthesis and the activity of the slt-II promoter of plasmid pADR-28. While a slight impact of growth temperature on SLT-II expression was observed, no impact of either osmolarity, pH, oxygen tension, acetates, iron level, or utilized carbon source could be demonstrated.
Lehrstuhl fäur Molekulare Infektionsbiologie, Universität Würzburg, Germany.
I
I
Mühldorfer
J
J
Hacker
G T
GT
Keusch
D W
DW
Acheson
H
H
Tschäpe
A V
AV
Kane
A
A
Ritter
T
T
Olschläger
A
A
Donohue-Rolfe
D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D004768:Enterotoxins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006463:Hemolytic-Uremic Syndrome / Q000209:etiology; D008969:Molecular Sequence Data; D009876:Operon; D011938:Rec A Recombinases / Q000235:genetics; D022641:Shiga Toxin 2
D001427:Bacterial Toxins; D004768:Enterotoxins; D022641:Shiga Toxin 2; D011938:Rec A Recombinases