Structural and functional characterization of DNA mismatch repair proteins for elucidation of the pathogenic mechanism of Lynch syndrome and drug discovery

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K07376
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 48040:Medical biochemistry-related
• Research Institution: Osaka Medical and Pharmaceutical University
• Principal Investigator: Kenji Fukui 大阪医科薬科大学, 医学部, 助教 (00466038)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: ミスマッチ修復 / MutL / X線結晶構造解析 / DNA修復 / 亜鉛 / カドミウム

Outline of Final Research Achievements

We characterized the MutL protein, which plays a central role in the DNA mismatch repair system. MutL undergoes a conformational change upon binding/hydrolyzing ATP, and cleaves mismatch-containing dsDNA. However, the catalytic mechanisms for ATP hydrolysis and DNA cleavage had remained unclear, which has been an obstacle in determining the pathogenicity of missense mutations in the mutL genes. In this study, the structures of the free, ADP-bound, and ATP-bound forms of the ATPase domain of MutL were determined by X-ray crystallography. Together with the results of kinetic analyses of the ATPase-mutant forms of the MutL, the catalytic mechanism for ATP hydrolysis was elucidated. The high resolution structure of the zinc-, cadmium-, and manganese-bound forms of the DNase domain of MutL were also determined by the X-ray crystallography, and the catalysis of the DNA cleavage MutL was elucidated to be performed by the two-metal-ion mechanism.

Free Research Field

タンパク質科学

Academic Significance and Societal Importance of the Research Achievements

MutL遺伝子におけるミスセンス変異はリンチ症候群の原因となり得る。しかし、病的な変異と中立な変異を区別する基準が不足していることが問題となっていた。今回、MutLのATPase活性とDNA切断活性の触媒メカニズム、つまりこれらの活性に必須の残基を明らかにしたことは、MutL遺伝子ミスセンス変異の病原性の判断に大きく貢献すると期待される。また、触媒メカニズムが明らかになったことで、ミスマッチ修復系を阻害する薬剤の開発が可能となった。