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PMID: 104955 Published · ppublish English Journal Article Research Support, U.S. Gov't, P.H.S.

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

Journal of bacteriology ·Vol. 137 ·No. 1 ·1979-01-00 ·Pages 137-45

Pfahl M

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.

MeSH Terms
Bacterial Proteins/isolation & purification,metabolism Escherichia coli/genetics Genes, Regulator Lac Operon Mutation Repressor Proteins/isolation & purification,metabolism Transcription Factors/metabolism beta-Galactosidase/biosynthesis
Chemicals
Bacterial Proteins Repressor Proteins Transcription Factors beta-Galactosidase
Authors & Affiliations
1 authors, click to expand affiliations / ORCID
Pfahl M
References (16)
16 references, click to expand
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Article Info
Journal
Journal of bacteriology
Abbr.
J Bacteriol
ISSN
0021-9193
Published
1979-01-00
Pages
137-45
Language
English
Region
United States
NLM ID
2985120R
PMCID
PMC218427
Subset
IM
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