Trasviña-Arenas Carlos H, Dissanayake Upeksha C, Tamayo Nikole, Hashemian Mohammad, Lin Wen-Jen, Demir Merve, Hoyos-Gonzalez Nallely, Fisher Andrew J, Cisneros G Andrés, Horvath Martin P, David Sheila S
Department of Chemistry, University of California, Davis, CA, USA.
Research Center on Aging, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico.
Nat Commun. 2025 Apr 16;16(1):3596. doi: 10.1038/s41467-025-58361-w.
MUTYH is a clinically important DNA glycosylase that thwarts mutations by initiating base-excision repair at 8-oxoguanine (OG):A lesions. The roles for its [4Fe-4S] cofactor in DNA repair remain enigmatic. Functional profiling of cancer-associated variants near the [4Fe-4S] cofactor reveals that most variations abrogate both retention of the cofactor and enzyme activity. Surprisingly, R241Q and N238S retained the metal cluster and bound substrate DNA tightly, but were completely inactive. We determine the crystal structure of human MUTYH bound to a transition state mimic and this shows that Arg241 and Asn238 build an H-bond network connecting the [4Fe-4S] cluster to the catalytic Asp236 that mediates base excision. The structure of the bacterial MutY variant R149Q, along with molecular dynamics simulations of the human enzyme, support a model in which the cofactor functions to position and activate the catalytic Asp. These results suggest that allosteric cross-talk between the DNA binding [4Fe-4S] cofactor and the base excision site of MUTYH regulate its DNA repair function.
MUTYH是一种临床上重要的DNA糖基化酶，它通过在8-氧代鸟嘌呤（OG）:A损伤处启动碱基切除修复来阻止突变。其[4Fe-4S]辅因子在DNA修复中的作用仍然不明。对[4Fe-4S]辅因子附近癌症相关变体的功能分析表明，大多数变异消除了辅因子的保留和酶活性。令人惊讶的是，R241Q和N238S保留了金属簇并紧密结合底物DNA，但完全没有活性。我们确定了与过渡态模拟物结合的人类MUTYH的晶体结构，这表明精氨酸241和天冬酰胺238构建了一个氢键网络，将[4Fe-4S]簇连接到介导碱基切除的催化天冬氨酸236。细菌MutY变体R149Q的结构，以及人类酶的分子动力学模拟，支持了一个模型，即辅因子的功能是定位和激活催化天冬氨酸。这些结果表明，DNA结合[4Fe-4S]辅因子与MUTYH的碱基切除位点之间的变构串扰调节其DNA修复功能。
