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AraC proteins with altered DNA sequence specificity which activate a mutant promoter in Escherichia coli.
- Source :
- Journal of Biological Chemistry; March 1988, Vol. 263 Issue: 9 p4400-4407, 8p
- Publication Year :
- 1988
-
Abstract
- We examined the recognition of the araBAD promoter by the AraC protein in the Escherichia coli arabinose operon. A mutant promoter, with base substitutions at positions contacted by AraC, was used to isolate suppressor mutations in araC by direct selection. Two hydroxylamine-induced araC mutations were isolated repeatedly; each contained a single amino acid substitution. When tested against a set of base substitution promoter mutants, one revertant, an Arg to His substitution at residue 250, displayed altered base specificity for a single position within the araBAD promoter. The other revertant, a Cys to Tyr substitution at residue 204, did not show consistent base-specific suppression. Neither demonstrated a higher affinity than the wild type protein for the mutant promoter in vitro. Both proteins suppress mutant sequences by a mechanism that does not appear to involve the formation of new net favorable contacts with the mutant base pairs of the promoter.
Details
- Language :
- English
- ISSN :
- 00219258 and 1083351X
- Volume :
- 263
- Issue :
- 9
- Database :
- Supplemental Index
- Journal :
- Journal of Biological Chemistry
- Publication Type :
- Periodical
- Accession number :
- ejs55972922
- Full Text :
- https://doi.org/10.1016/S0021-9258(18)68940-9