In vitro interactions of integration host factor with the ompF promoter-regulatory region of Escherichia coli.
Previous work has shown that integration host factor (IHF) mutants have increased expression and altered osmoregulation of OmpF, a major Escherichia coli outer membrane protein. By in vitro analysis the possibility was investigated that IHF interacts directly with the ompF promoter region. Gel retardation assays and DNase I protection experiments showed that IHF binds to two sites in the ompF promoter region centered at positions -180 and -60 relative to the start of transcription. Gel electrophoresis studies with circularly permuted ompF promoter fragments indicated that IHF binding strongly increased a small intrinsic bend in the ompF promoter region. The addition of IHF to a purified in vitro transcription system strongly and specifically inhibited ompF transcription. This inhibition was reversed by increasing the concentration of OmpR, a positive activator required for ompF expression, suggesting that IHF may inhibit ompF transcription by altering how OmpR interacts with the ompF promoter.
Ramani
N
N
Department of Biochemistry and Cell Biology, State University of New York, Stony Brook 11794-5215.
Huang
L
L
Freundlich
M
M
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics*; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation / Q000187:drug effects; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014158:Transcription, Genetic / Q000187:drug effects
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D034982:Integration Host Factors