Open AccessEscherichia coli ArgR mutants defective in cer /Xer recombination, but not in DNA binding
Author(s) -
Sénéchal Hélène,
Delesques Jérémy,
Szatmari George
Publication year - 2010
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2010.01921.x
Subject(s) - repressor , mutant , repressor lexa , escherichia coli , lac repressor , dna , microbiology and biotechnology , biology , sos response , mutagenesis , chemistry , lac operon , gene , biochemistry , gene expression
The Escherichia coli arginine repressor (ArgR) is an l ‐arginine‐dependent DNA‐binding protein that controls the expression of the arginine biosynthetic genes and is required as an accessory factor for Xer site‐specific recombination at cer and related recombination sites in plasmids. We used the technique of pentapeptide scanning mutagenesis to isolate a series of ArgR mutants that were considerably reduced in cer recombination, but were still able to repress an argA ∷ lacZ fusion. DNA sequence analysis showed that all of the mutants mapped to the same nucleotide, resulting in a five amino acid insertion between residues 149 and 150 of ArgR, corresponding to the end of the α6 helix. A truncated ArgR containing a stop codon at residue 150 displayed the same phenotype as the protein with the five amino acid insertion, and both mutants displayed sequence‐specific DNA‐binding activity that was l ‐arginine dependent. These results show that the C‐terminus of ArgR is more important in cer /Xer site‐specific recombination than in DNA binding.