Centrosome Protein Centrin 2/Caltractin 1 Is Part of the Xeroderma Pigmentosum Group C Complex That Initiates Global Genome Nucleotide Excision Repair

Marito Araki,Chikahide Masutani,Mitsuyo Takemura,Akio Uchida,Kaoru Sugasawa,Jun Kondoh,Yoshiaki Ohkuma,Fumio Hanaoka

doi:10.1074/jbc.m100855200

Abstract

Nucleotide excision repair (NER) is carried out by xeroderma pigmentosum (XP) factors. Before the excision reaction, DNA damage is recognized by a complex originally thought to contain the XP group C responsible gene product (XPC) and the human homologue of Rad23 B (HR23B). Here, we show that centrin 2/caltractin 1 (CEN2) is also a component of the XPC repair complex. We demonstrate that nearly all XPC complexes contain CEN2, that CEN2 interacts directly with XPC, and that CEN2, in cooperation with HR23B, stabilizes XPC, which stimulates XPC NER activity in vitro. CEN2 has been shown to play an important role in centrosome duplication. Thus, those findings suggest that the XPC-CEN2 interaction may reflect coupling of cell division and NER.

Highlights

Centrin found in the centrosomes of a wide variety of organisms [1] is a member of the highly conserved superfamily of calcium binding EF-hand proteins
Roles of centrin 2/caltractin 1 (CEN2) in the XP group C responsible gene product (XPC) Complex—In this study, we have demonstrated that CEN2 is a component of the XPC complex (Figs. 1 and 2) that directly interacts with XPC (Fig. 3)
We could detect neither XPC nor homologue of Rad23 B (HR23B) in a partially purified centrosome fraction from HeLa cells. These observations strongly suggest that CEN2 has a role in Nucleotide excision repair (NER) in human nuclei that is distinct from its function in the centrosome

Summary

Introduction

Centrin (caltractin) found in the centrosomes of a wide variety of organisms [1] is a member of the highly conserved superfamily of calcium binding EF-hand proteins. NER reaction consists of four steps: 1) damage recognition, 2) excision of the damaged DNA by creating incisions on both sides of the lesion, 3) gap-filling by DNA polymerase activity, and 4) ligation [18]. The XPC complex acts as a key component of global genome nucleotide excision repair (GGR), a NER subpathway, by functioning as the initial damage detector [24]. This complex was isolated as a heterodimeric complex and consists of the XPC gene product (XPC) and the human homologue of Rad B (HR23B) protein [25]. The mechanism of NER stimulation by HR23B is still poorly understood [31]

Methods

Results

Conclusion