Escherichia coli mismatch repair protein MutL interacts with the clamp loader subunits of DNA polymerase III.
It has been hypothesized that DNA mismatch repair (MMR) is coupled with DNA replication; however, the involvement of DNA polymerase III subunits in bacterial DNA MMR has not been clearly elucidated. In an effort to better understand the relationship between these 2 systems, the potential interactions between the Escherichia coli MMR protein and the clamp loader subunits of E. coli DNA polymerase III were analyzed by far western blotting and then confirmed and characterized by surface plasmon resonance (SPR) imaging. The results showed that the MMR key protein MutL could directly interact with both the individual subunits delta, delta', and gamma and the complex of these subunits (clamp loader). Kinetic parameters revealed that the interactions are strong and stable, suggesting that MutL might be involved in the recruitment of the clamp loader during the resynthesis step in MMR. The interactions between MutL, the delta and gamma subunits, and the clamp loader were observed to be modulated by ATP. Deletion analysis demonstrated that both the N-terminal residues (1-293) and C-terminal residues (556-613) of MutL are required for interacting with the subunits delta and delta'. Based on these findings and the available information, the network of interactions between the MMR components and the DNA polymerase III subunits was established; this network provides strong evidence to support the notion that DNA replication and MMR are highly associated with each other.
Li
Feng
F
State Key Laboratory of Agricultural Microbiology, Huazhong Agriculture University, Wuhan, China.
Liu
Qin
Q
Chen
Yuan-Yuan
YY
Yu
Zi-Niu
ZN
Zhang
Zhi-Ping
ZP
Zhou
Ya-Feng
YF
Deng
Jiao-Yu
JY
Bi
Li-Jun
LJ
Zhang
Xian-En
XE
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D015153:Blotting, Western; D053843:DNA Mismatch Repair; D004258:DNA Polymerase III / Q000378:metabolism*; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D000070956:MutL Proteins; D021122:Protein Subunits / Q000378:metabolism; D020349:Surface Plasmon Resonance
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D004258:DNA Polymerase III; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins