title: Two-stage dynamic DNA quality check by xeroderma pigmentosum group C protein.
abstract: Xeroderma pigmentosum group C (XPC) protein initiates the DNA excision repair of helix-distorting base lesions. To understand how this versatile subunit searches for aberrant sites within the vast background of normal genomic DNA, the real-time redistribution of fluorescent fusion constructs was monitored after high-resolution DNA damage induction. Bidirectional truncation analyses disclosed a surprisingly short recognition hotspot, comprising approximately 15% of human XPC, that includes two beta-hairpin domains with a preference for non-hydrogen-bonded bases in double-stranded DNA. However, to detect damaged sites in living cells, these DNA-attractive domains depend on the partially DNA-repulsive action of an adjacent beta-turn extension that promotes the mobility of XPC molecules searching for lesions. The key function of this dynamic interaction surface is shown by a site-directed charge inversion, which results in increased affinity for native DNA, retarded nuclear mobility and diminished repair efficiency. These studies reveal a two-stage discrimination process, whereby XPC protein first deploys a dynamic sensor interface to rapidly interrogate the double helix, thus forming a transient recognition intermediate before the final installation of a more static repair-initiating complex.
authors.affiliation: Institute of Pharmacology and Toxicology, University of Zürich-Vetsuisse, Zürich, Switzerland.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Camenisch
authors.forename: Daniel
authors.initials: D
authors.lastname: Träutlein
authors.forename: Flurina C
authors.initials: FC
authors.lastname: Clement
authors.forename: Jia
authors.initials: J
authors.lastname: Fei
authors.forename: Alfred
authors.initials: A
authors.lastname: Leitenstorfer
authors.forename: Elisa
authors.initials: E
authors.lastname: Ferrando-May
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Naegeli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006224:Cricetinae; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D004268:DNA-Binding Proteins; C086984:XPC protein, human; D004247:DNA