DNA-binding properties of the transcription activator (OmpR) for the upstream sequences of ompF in Escherichia coli are altered by envZ mutations and medium osmolarity.
نویسندگان
چکیده
Expression in Escherichia coli of the genes that encode the major outer membrane porin proteins (OmpF and OmpC) is regulated by the transcription activator protein OmpR and the receptorlike protein EnvZ, which is located in the inner membrane. Using synthesized oligonucleotide fragments containing the OmpR-binding site of ompF, we show that soluble extracts and partially purified OmpR derived from both the parent strain grown in nutrient broth plus 20% sucrose and the envZ11 strain grown in nutrient broth produced high-affinity DNA-binding activity, whereas soluble extracts from the parent strain grown in nutrient broth produced low-affinity binding. We also show that the soluble extracts from the envZ22(Am) strain grown in nutrient broth did not produce detectable bound forms of the ompF fragments, but low levels of DNA binding were detected with soluble extracts of the envZ22 strain grown in nutrient broth plus sucrose. In addition, the time course of the repression of OmpF synthesis produced by a shift to high-osmolarity growth medium was correlated with an increase in the DNA-binding affinity of soluble extracts to the ompF fragment. These results provide evidence that envZ function influences the DNA-binding activity of OmpR and suggest that high-affinity binding of OmpR to the upstream sequences of ompF is correlated with the repression of OmpF production.
منابع مشابه
Interaction of a transcriptional activator, OmpR, with reciprocally osmoregulated genes, ompF and ompC, of Escherichia coli.
The ompB locus, comprised of the genes ompR and envZ, regulates the expression of the genes ompF and ompC that encode the major porin proteins in the outer membrane of Escherichia coli K-12. OmpR is believed to activate transcription of ompF and ompC in a reciprocal manner depending upon the osmolarity of the culture medium. We were able to purify OmpR to homogeneity and to characterize its int...
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ورودعنوان ژورنال:
- Journal of bacteriology
دوره 171 6 شماره
صفحات -
تاریخ انتشار 1989