Escherichia coli lac repressor-lac operator interaction and the influence of allosteric effectors

Nancy C Horton, Mitchell Lewis, Ponzy Lu

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The wild type E. coli lac operator is embedded in a 35 base-pair DNA sequence containing extensive 2-fold symmetry, suggesting a symmetric repressor operator complex. However, deviations from strict 2-fold symmetry occur at the central base-pair and at three additional base-pairs. Using an operator fragment binding analysis we have determined: (a) a relative contribution each pair provides to the lac repressor-lac operator DNA complex, (b) the operator DNA length necessary for maximum binding to lac repressor; and (c) the contribution of the several non-symmetric base in the wild-type operator to the binding affinity. Since lac repressor-lac operator DNA interaction is reduced upon binding of the gratuitous inducer, isopropyl-β-D-galactoside (IPTG), the same DNA fragment binding analysis was performed with the low affinity form of lac repressor. In the presence of inducer, the affinity for the left half site of the wild-type lac operator is reduced without significant reduction on the right half of the operator. Conversely, the anti-inducer orthonitrophenylfucoside (ONPF) which stabilizes the lac repressor-lac operator complex increases the binding affinity, particularly to the right half of the operator.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalJournal of Molecular Biology
Volume265
Issue number1
DOIs
StatePublished - Jan 10 1997
Externally publishedYes

Fingerprint

Lac Repressors
Escherichia coli
Base Pairing
DNA
Isopropyl Thiogalactoside
Galactosides

Keywords

  • Allosteric protein
  • lac operator
  • lac repressor
  • Protein-DNA interaction

ASJC Scopus subject areas

  • Virology

Cite this

Escherichia coli lac repressor-lac operator interaction and the influence of allosteric effectors. / Horton, Nancy C; Lewis, Mitchell; Lu, Ponzy.

In: Journal of Molecular Biology, Vol. 265, No. 1, 10.01.1997, p. 1-7.

Research output: Contribution to journalArticle

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