XAB2, a Novel Tetratricopeptide Repeat Protein Involved in Transcription-coupled DNA Repair and Transcription

Yoshimichi Nakatsu,Hiroshi Asahina,Elisabetta Citterio,Suzanne Rademakers,Wim Vermeulen,Shinya Kamiuchi,Jing-Ping Yeo,Min-Cheh Khaw,Masafumi Saijo,Naohiko Kodo,Toshiro Matsuda,Jan H.J Hoeijmakers,Kiyoji Tanaka

doi:10.1074/jbc.m004936200

Yoshimichi Nakatsu, Hiroshi Asahina + Show 11 more

Open Access

https://doi.org/10.1074/jbc.m004936200

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Abstract

Nucleotide excision repair is a highly versatile DNA repair system responsible for elimination of a wide variety of lesions from the genome. It is comprised of two subpathways: transcription-coupled repair that accomplishes efficient removal of damage blocking transcription and global genome repair. Recently, the basic mechanism of global genome repair has emerged from biochemical studies. However, little is known about transcription-coupled repair in eukaryotes. Here we report the identification of a novel protein designated XAB2 (XPA-binding protein 2) that was identified by virtue of its ability to interact with XPA, a factor central to both nucleotide excision repair subpathways. The XAB2 protein of 855 amino acids consists mainly of 15 tetratricopeptide repeats. In addition to interacting with XPA, immunoprecipitation experiments demonstrated that a fraction of XAB2 is able to interact with the transcription-coupled repair-specific proteins CSA and CSB as well as RNA polymerase II. Furthermore, antibodies against XAB2 inhibited both transcription-coupled repair and transcription in vivo but not global genome repair when microinjected into living fibroblasts. These results indicate that XAB2 is a novel component involved in transcription-coupled repair and transcription.

Highlights

Nucleotide excision repair is a highly versatile DNA repair system responsible for elimination of a wide variety of lesions from the genome
We found a novel protein, XAB2, which interacts with TCRspecific CSA, CSB proteins, and RNA polymerase II as well as DNA repair and transcription
100 100 a Unscheduled DNA synthesis (DNA repair synthesis) levels expressed as a percentage of UDS compared with noninjected neighboring cells. b Percentage of the residual UDS in xeroderma pigmentosum (XP)-C cells was 25 Ϯ 5% of normal level. c Percentage of RNA synthesis recovery after UV exposure in injected cells compared with noninjected neighboring cells. d Percentage of overall RNA synthesis in nonirradiated injected cells. e All experiments were repeated at least three times with the following exceptions

Summary

A Novel TPR Protein in DNA Repair and Transcription

By DNA ligase (see Refs. 14 and 17 for recent reviews and specific references therein). We have previously shown that CSB is associated with RNA polymerase II in vivo [21], and we and others have shown that CSB has a DNA-dependent ATPase activity but no detectable classical helicase activity [22, 23]. Since both CSB and Mfd contain helicase motifs, CSB may play a role equivalent to Mfd in mammalian cells. We found that XAB2 associates with both TCR-specific factors CSA and CSB and with RNA polymerase II. Microinjection of anti-XAB2 antibodies inhibited transcription as well as TCR but not GGR, suggesting that XAB2 is a novel factor participating in TCR and transcription itself

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION