Evidence of an unusually long operator for the fur repressor in the aerobactin promoter of Escherichia coli.
Production of the siderophore aerobactin in Escherichia coli is transcriptionally metalloregulated through the iron-dependent binding of the Fur (ferric uptake regulator) to a large region (>100 base pairs) within the cognate promoter in the pColV-K30 plasmid. We show in this article that such an unusually long operator results from the specific addition of degenerate repeats 5'-NAT(A/T)AT-3' and not from a fortuitous occupation of the DNA adjacent to the primary binding sites by an excess of the repressor. Furthermore, the protection pattern revealed by DNase I and hydroxyl radical footprinting reflected a side-by-side oligomerization of the protein along an extended DNA stretch. This type of DNA-protein interactions is more like those observed in some eukaryotic factors and nucleoid-associated proteins than typical of specific prokaryotic regulators.
Escolar
L
L
Department of Microbial Biotechnology, Centro Nacional de Biotecnologia CSIC, Campus de Cantoblanco, 28049 Madrid, Spain.
Pérez-Martín
J
J
de Lorenzo
V
V
D020121:5' Untranslated Regions / Q000235:genetics; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D018983:DNA Footprinting; D003850:Deoxyribonuclease I; D004926:Escherichia coli / Q000235:genetics*; D016368:Frameshift Mutation; D014644:Genetic Variation; D006877:Hydroxamic Acids / Q000378:metabolism*; D017665:Hydroxyl Radical; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000302:isolation & purification / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism
D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D006877:Hydroxamic Acids; D012097:Repressor Proteins; D017262:Siderophores; C068477:ferric uptake regulating proteins, bacterial; C031819:aerobactin; D017665:Hydroxyl Radical; D007501:Iron; D003850:Deoxyribonuclease I