Escherichia coli ArgR mutants defective in cer/Xer recombination, but not in DNA binding.
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 alpha6 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.
Sénéchal
Hélène
H
Département de Biochimie, Université de Montréal, Montréal, QC, Canada.
Delesques
Jérémy
J
Szatmari
George
G
D000595:Amino Acid Sequence; D002876:Chromosomes, Bacterial; D018389:Codon, Nonsense; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D050505:Mutant Proteins / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion
C490177:ArgR protein, E coli; D018389:Codon, Nonsense; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D050505:Mutant Proteins; D012097:Repressor Proteins