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Human nucleotide excision repair protein XPA: Extended X‐ray absorption fine‐structure evidence for a metal‐binding domain
Author(s) -
Hess Nancy J.,
Buchko Garry W.,
Ni Shuisong,
Thrall Brian D.,
Kennedy Michael A.,
Conradson Steven D.,
Espinosa F. Javier
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070912
Subject(s) - nucleotide excision repair , dna , dna repair , zinc finger , xeroderma pigmentosum , chemistry , cysteine , zinc , biology , microbiology and biotechnology , crystallography , biochemistry , enzyme , gene , transcription factor , organic chemistry
The ubiquitous, multi‐enzyme, nucleotide excision repair (NER) pathway is responsible for correcting a wide range of chemically and structurally distinct DNA lesions in the eukaryotic genome. Human XPA, a 31 kDa, zinc‐associated protein, is thought to play a major NER role in the recognition of damaged DNA and the recruitment of other proteins, including RPA, ERCC1, and TFIIH, to repair the damage. Sequence analyses and genetic evidence suggest that zinc is associated with a C4‐type motif, C10S‐X 2 ‐C108‐X 17 ‐C126‐X 2 ‐C129, located in the minimal DNA binding region of XPA (M98‐F219). The zinc‐associated motif is essential for damaged DNA recognition. Extended X‐ray absorption fine structure (EXAFS) spectra collected on the zinc associated minimal DNA‐binding domain of XPA (ZnXPA‐MBD) show directly, for the first time, that the zinc is coordinated to the sulfur atoms of four cysteine residues with an average Zn‐S bond length of 2.34 ± 0.01 Å. XPA‐MBD was also expressed in minimal medium supplemented with cobalt nitrate to yield a blue‐colored protein that was primarily (>95%) cobalt associated (CoXPA‐MBD). EXAFS spectra collected on CoXPA‐MBD show that the cobalt is also coordinated to the sulfur atoms of four cysteine residues with an average Co‐S bond length of 2.33 ± 0.02 Å.