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. 1979 Jan;137(1):137–145. doi: 10.1128/jb.137.1.137-145.1979

Tight-binding repressors of the lac operon: selection system and in vitro analysis.

M Pfahl
PMCID: PMC218427  PMID: 104955

Abstract

The isolation and characterization of altered repressors of the lac operon which have an increased affinity for an operator should give useful clues about the molecular basis for the very tight and specific interaction between repressor and operator. A selection system has been devised which allows the isolation of such repressor mutants. This system selects for mutant repressors which can overcome lac operator-constitutive (Oc) mutations. By using in vivo assays, 24 candidates were obtained which, compared with wild type, have an increased trans effect of their repressor on one or several Oc operators. Three of these candidates have been investigated in vitro; the affinity of their repressor for inducer was unchanged, whereas the affinity for wild-type operator was increased 15-, 86-, and 262-fold, respectively.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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