PMID: 8260490
Myers LC, Verdine GL, Wagner G
Solution structure of the DNA methyl phosphotriester repair domain of Escherichia coli Ada.
Biochemistry. 1993 Dec 28;32(51):14089-94.
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.