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Binding of Escherichia coli lexA repressor to the RecA operator
Author(s) -
Shaner Sandra L.,
Gaissarian Elisabeth S.
Publication year - 1996
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/(sici)1099-1352(199634/12)9:5/6<468::aid-jmr284>3.0.co;2-w
Subject(s) - repressor lexa , escherichia coli , repressor , chemistry , operator (biology) , microbiology and biotechnology , biology , biochemistry , gene , transcription factor
Equilibrium binding of Escherichia coli LexA repressor to the recA operator was studied by the polyacrylamide gel mobility shift assay as a function of solution conditions. In the presence of NaCl at 20°C, there was a significant salt dependence in binding to the recA operator, typical for protein–nucleic acid interactions with some electrostatic contribution to the binding free energy. In preliminary experiments in which the anion of the Na + salt was changed from chloride to fluoride, little change was found with anion identity. This indicates that the salt effect on the binding interaction arises solely from the polyelectrolyte effect, not from anion binding or release by the protein upon complex formation. Increasing the temperature to 37°C changed the binding affinity for complex formation at any given salt concentration and resulted in a change in the sensitivity of complex formation to NaCl concentration. Quantitative analysis of the data to obtain equilibrium binding constants is discussed.