UVH6, a Plant Homolog of the Human/Yeast TFIIH Transcription Factor Subunit XPD/RAD3, Regulates Cold-stress Genes in Arabidopsis thaliana

The UVH6 gene from Arabidopsis thaliana is predicted to function in transcription regulation, based on known activities of its human and yeast homologs. In this study, we show that uvh6-1 mutants are ultra-sensitive to cold and suggest that this defect results from reduced expression of cold-stress genes. Comparison of mRNA levels in cold-treated wild-type and uvh6-1 plants reveals that expression of two cold-stress genes (Cor6.6 and Cor15a) is impaired in the mutant. In contrast, the mutant shows normal cold induction of three transcription factor genes (CBF1, 2, 3), which regulate these Cor genes, and normal induction of several additional CBF-targeted genes. Thus, we propose that UVH6 promotes cold resistance by specifically regulating transcription of Cor6.6 and Cor15a genes. We further find features among the regulatory sites in the Cor6.6 and Cor15a promoters which suggest unique regulation of these genes.