Steady-state ATPase activity of E. coli MutS modulated by its dissociation from heteroduplex DNA.
The ability of MutS to recognize mismatched DNA is required to initiate a mismatch repair (MMR) system. ATP binding and hydrolysis are essential in this process, but their role in MMR is still not fully understood. In this study, steady-state ATPase activities of MutS from Escherichia coli were investigated using the spectrophotometric method with a double end-blocked heteroduplex containing gapped bases. The ATPase activities of MutS increased as the number of gapped bases increased in a double end-blocked heteroduplex with 2-8 gapped bases in the chain, indicating that MutS dissociates from DNA when it reaches a scission during movement along the DNA. Since movement of MutS along the chain does not require extensive ATP hydrolysis and the ATPase activity is only enhanced when MutS dissociates from a heteroduplex, these results support the sliding clamp model in which ATP binding by MutS induces the formation of a hydrolysis-independent sliding clamp.
Heo
Seong-Dal
SD
Department of Chemistry, Pohang University of Science and Technology, San 31, Hyoja-Dong, Pohang, Gyungbuk 790-784, Republic of Korea.
Cho
Minseon
M
Ku
Ja Kang
JK
Ban
Changill
C
D000251:Adenosine Triphosphatases / Q000737:chemistry*; D004269:DNA, Bacterial / Q000737:chemistry*; D004789:Enzyme Activation; D029968:Escherichia coli Proteins / Q000737:chemistry*; D051719:MutS DNA Mismatch-Binding Protein / Q000737:chemistry*; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry*
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D009692:Nucleic Acid Heteroduplexes; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein