PMID:9352908
| Citation |
Donato, GM, Lelivelt, MJ and Kawula, TH (1997) Promoter-specific repression of fimB expression by the Escherichia coli nucleoid-associated protein H-NS. J. Bacteriol. 179:6618-25 |
|---|---|
| Abstract |
The H-NS protein is a major component of the Escherichia coli nucleoid. Mutations in hns, the gene encoding H-NS, have pleiotropic effects on the cell altering both the expression of a variety of unlinked genes and the inversion rate of the DNA element containing the fimA promoter. We investigated the interaction between H-NS and fimB, the gene encoding the bidirectional recombinase that catalyzes fimA promoter flipping. In beta-galactosidase assays, we found that fimB expression increased approximately fivefold in an hns2-tetR insertion mutant. In gel mobility shift assays with purified H-NS, we have also shown that H-NS bound directly and cooperatively to the fimB promoter region with greater affinity than for any other known H-NS-regulated gene. Furthermore, this high-affinity interaction resulted in a promoter-specific inhibition of fimB transcription. The addition of purified H-NS to an in vitro transcription system yielded a fivefold or greater reduction in fimB-specific mRNA production. However, the marked increase in cellular FimB levels in the absence of H-NS was not the primary cause of the mutant rapid inversion phenotype. These results are discussed in regard to both H-NS as a transcriptional repressor of fimB expression and its role in regulating type 1 pilus promoter inversion. |
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| Keywords |
Bacterial Proteins/biosynthesis; Bacterial Proteins/genetics; DNA Nucleotidyltransferases/biosynthesis; DNA-Binding Proteins/biosynthesis; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli Proteins; Fimbriae Proteins; Gene Expression Regulation, Bacterial; Integrases; Mutation; Promoter Regions, Genetic; Protein Binding; RNA, Bacterial/analysis; RNA, Messenger/analysis; Transcription, Genetic |
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