Myers L C, Verdine G L, Wagner G
Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138.
Biochemistry. 1993 Dec 28;32(51):14089-94. doi: 10.1021/bi00214a003.
The Escherichia coli Ada protein repairs methyl phosphotriesters in DNA by direct, irreversible methyl transfer to one of its own cysteine residues. The methyl-transfer process appears to be autocatalyzed by coordination of the acceptor residue, Cys-69, to a tightly bound zinc ion. Upon methyl transfer, Ada acquires the ability to bind DNA sequence-specifically and thereby to induce genes that confer resistance to methylating agents. The solution structure of an N-terminal 10-kDa fragment of Ada, which retains zinc binding and DNA methyl phosphotriester repair activities, was determined using multidimensional heteronuclear nuclear magnetic resonance techniques. The structure reveals a zinc-binding motif unlike any observed thus far in transcription factors or zinc-containing enzymes and provides insight into the mechanism of metalloactivated DNA repair.
大肠杆菌Ada蛋白通过将甲基直接不可逆地转移到自身的一个半胱氨酸残基上来修复DNA中的甲基磷酸三酯。甲基转移过程似乎是由受体残基Cys-69与紧密结合的锌离子配位自动催化的。甲基转移后，Ada获得了序列特异性结合DNA的能力，从而诱导赋予对甲基化剂抗性的基因。使用多维异核核磁共振技术确定了Ada N端10 kDa片段的溶液结构，该片段保留了锌结合和DNA甲基磷酸三酯修复活性。该结构揭示了一种不同于迄今为止在转录因子或含锌酶中观察到的锌结合基序，并为金属激活的DNA修复机制提供了深入了解。
