Escherichia coli MutS,L modulate RuvAB-dependent branch migration between diverged DNA.
This study examines the interaction between Escherichia coli MutS,L and E. coli RuvAB during E. coli RecA-promoted strand exchange. RuvAB is a branch migration complex that stimulates heterologous strand exchange. Previous studies indicate that RuvAB increases the rate at which heteroduplex products are formed by RecA, that RuvA and RuvB are required for this stimulation, and that RuvAB does not stimulate homologous strand exchange. This study indicates that MutS,L inhibit the formation of full-length heteroduplex DNA between M13-fd DNA in the presence of RuvAB, such that less than 2% of the linear substrate is converted to product. Inhibition depends on the time at which MutS,L are added to the reaction and is strongest when MutS,L are added during initiation. The kinetics of the strand exchange reaction suggest that MutS,L directly inhibit RuvAB-dependent branch migration in the absence of RecA. The inhibition requires the formation of base-base mismatches and ATP utilization; no effect on RuvAB-promoted strand exchange is seen if an ATP-deficient mutant of MutS (MutS501) is included in the reaction instead of wild-type MutS. These results are consistent with a role for MutS,L in maintaining genomic stability and replication fidelity.
Fabisiewicz
A
A
Laboratory of Molecular Genetics, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Worth
L
L
D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000378:metabolism*; D017104:Bacteriophage M13 / Q000235:genetics; D020137:Base Pair Mismatch; D004265:DNA Helicases; D004260:DNA Repair; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007700:Kinetics; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein
D001426:Bacterial Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; C061260:RuvB protein, Bacteria; C071059:Holliday junction DNA helicase, E coli; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli; D004265:DNA Helicases