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Mutant Escherichia coli arginine repressor proteins that fail to bind l ‐arginine, yet retain the ability to bind their normal DNA‐binding sites
Author(s) -
Burke Mary,
Merican Amir F.,
Sherratt David J.
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb00455.x
Subject(s) - repressor , biology , mutant , escherichia coli , arginine , dna , mutagenesis , dna binding protein , microbiology and biotechnology , binding site , biochemistry , gene , amino acid , gene expression , transcription factor
Summary The Escherichia coli arginine repressor (ArgR) is an l ‐arginine‐dependent DNA‐binding protein that controls expression of the arginine biosynthetic genes and is required as an accessory protein in Xer site‐specific recombination at cer and related recombination sites in plasmids. Site‐directed mutagenesis was used to isolate two mutants of E. coli ArgR that were defective in arginine binding. Results from in vivo and in vitro experiments demonstrate that these mutants still act as repressors and bind their specific DNA sequences in an arginine‐independent manner. Both mutants support Xer site‐specific recombination at cer. One of the mutant proteins was purified and shown to bind to its DNA target sequences in vitro with different affinity and as a different molecular species to wild‐type ArgR.