Isolation of XAB2 Complex Involved in Pre-mRNA Splicing, Transcription, and Transcription-coupled Repair*
- Isao Kuraoka‡§,1,
- Shinsuke Ito‡,
- Tadashi Wada¶,
- Mika Hayashida‡,
- Lily Lee‡,2,
- Masafumi Saijo‡§,
- Yoshimichi Nakatsu‡,3,
- Megumi Matsumoto∥,
- Tsukasa Matsunaga∥,
- Hiroshi Handa¶,
- Jun Qin**,
- Yoshihiro Nakatani‡‡ and
- Kiyoji Tanaka‡§,4
- ‡Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University and §Solution-oriented Research for Science and Technology, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan, ∥Laboratory of Human Molecular Genetics, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan, ¶Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, Yokohama 226-8501, Japan, the **Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, and the ‡‡Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115
- ↵1 To whom correspondence may be addressed. Tel.: 81-92-541-3231; Fax: 81-92-542-8534; E-mail: ikuraoka{at}nk-cc.go.jp. 4 To whom correspondence may be addressed. Tel.: 81-6-6879-7971; Fax: 81-6-6877-9136; E-mail: ktanaka{at}fbs.osaka-u.ac.jp.
Abstract
Nucleotide excision repair is a versatile repair pathway that counteracts the deleterious effects of various DNA lesions. In nucleotide excision repair, there is a transcription-coupled repair (TCR) pathway that focuses on DNA damage that blocks RNA polymerase IIo in transcription elongation. XAB2 (XPA-binding protein 2), containing tetratricopeptide repeats, has been isolated by virtue of its ability to interact with xeroderma pigmentosum group A protein (XPA). Moreover, XAB2 has been shown to interact with Cockayne syndrome group A and B proteins (CSA and CSB) and RNA polymerase II, as well as XPA, and is involved in TCR and transcription. Here we purified XAB2 as a multimeric protein complex consisting of hAquarius, XAB2, hPRP19, CCDC16, hISY1, and PPIE, which are involved in pre-mRNA splicing. Knockdown of XAB2 with small interfering RNA in HeLa cells resulted in a hypersensitivity to killing by UV light and a decreased recovery of RNA synthesis after UV irradiation and regular RNA synthesis. Enhanced interaction of XAB2 with RNA polymerase IIo or XPA was observed in cells treated with DNA-damaging agents, indicating DNA damage-responsive activity of the XAB2 complex. These results indicated that the XAB2 complex is a multifunctional factor involved in pre-mRNA splicing, transcription, and TCR.
- Received August 10, 2007.
- Revision received October 29, 2007.
- The American Society for Biochemistry and Molecular Biology, Inc.
