THE 1ST ZINC-BINDING DOMAIN OF UVRA IS NOT ESSENTIAL FOR UVRABC-MEDIATED DNA EXCISION-REPAIR

Specific mutations in uvrA were introduced to analyze the role of the zinc-binding domains of the protein in DNA excision repair. Zinc-coord inating cysteines were substituted into non-coordinating serine or gly cine residues. Mutations leading to changes in the second zinc-binding domain had a profound effect on UV survival in vivo; however these mu tant proteins could not be isolated for in vitro analyses. Amino acid substitutions in the first zinc-binding domain had very little effect on UV survival in vivo. In vitro analyses showed that although this do main no longer coordinates zinc, ATPase activity, helicase activity, D NA binding, incision of damaged DNA and DNA repair synthesis appeared to be normal. Therefore it seems that the first zinc-binding domain of UvrA is not essential for DNA excision repair.