Y. Nakatsu et al., XAB2, a novel tetratricopeptide repeat protein involved in transcription-coupled DNA repair and transcription, J BIOL CHEM, 275(45), 2000, pp. 34931-34937
Nucleotide excision repair is a highly versatile DNA repair system responsi
ble for elimination of a wide variety of lesions from the genome. It is com
prised of two subpathways: transcription-coupled repair that accomplishes e
fficient removal of damage blocking transcription and global genome repair,
Recently, the basic mechanism of global genome repair has emerged from bio
chemical studies. However, little is known about transcription-coupled repa
ir in eukaryotes, Here we report the identification of a novel protein desi
gnated XAB2 (XPA-binding protein 2) that was identified by virtue of its ab
ility to interact with XPA, a factor central to both nucleotide excision re
pair subpathways, The XAB2 protein of 855 amino acids consists mainly of 15
tetratricopeptide repeats. In addition to interacting with XPA, immunoprec
ipitation experiments demonstrated that a fraction of XAB2 is able to inter
act with the transcription-coupled repair-specific proteins CSA and CSB as
well as RNA polymerase II. Furthermore, antibodies against XAB2 inhibited b
oth transcription-coupled repair and transcription in vivo but not global g
enome repair when microinjected into living fibroblasts. These results indi
cate that XAB2 is a novel component involved in transcription-coupled repai
r and transcription.