title: Structure-function analysis of the EF-hand protein centrin-2 for its intracellular localization and nucleotide excision repair.
abstract: Centrin-2 is an evolutionarily conserved, calmodulin-related protein, which is involved in multiple cellular functions including centrosome regulation and nucleotide excision repair (NER) of DNA. Particularly to exert the latter function, complex formation with the XPC protein, the pivotal NER damage recognition factor, is crucial. Here, we show that the C-terminal half of centrin-2, containing two calcium-binding EF-hand motifs, is necessary and sufficient for both its localization to the centrosome and interaction with XPC. In XPC-deficient cells, nuclear localization of overexpressed centrin-2 largely depends on co-overexpression of XPC, and mutational analyses of the C-terminal domain suggest that XPC and the major binding partner in the centrosome share a common binding surface on the centrin-2 molecule. On the other hand, the N-terminal domain of centrin-2 also contains two EF-hand motifs but shows only low-binding affinity for calcium ions. Although the N-terminal domain is dispensable for enhancement of the DNA damage recognition activity of XPC, it contributes to augmenting rather weak physical interaction between XPC and XPA, another key factor involved in NER. These results suggest that centrin-2 may have evolved to bridge two protein factors, one with high affinity and the other with low affinity, thereby allowing delicate regulation of various biological processes.
authors.affiliation: Biosignal Research Center, Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo 657-8501, Japan.
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Nishi
authors.forename: Wataru
authors.initials: W
authors.lastname: Sakai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tone
authors.forename: Fumio
authors.initials: F
authors.lastname: Hanaoka
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sugasawa
mesh_terms: D002135:Calcium-Binding Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D014466:Ultraviolet Rays; D051760:Xeroderma Pigmentosum Group A Protein / Q000378:metabolism
chemical_list: C472752:CETN2 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D051760:Xeroderma Pigmentosum Group A Protein; C086984:XPC protein, human