Abstract
Photolyase is an enzyme that repairs ultraviolet (W-damaged DNA by photoreactivation. In higher plants, accumulation of photolyase (PHRI) mRNA is induced by either W or visible light. In order to know the molecular mechanism by which PHRl gene expression is induced by light, we have determined the genomic structure and the 5′-flanking sequence of the Arabidopsis PHRl gene. The PHRl gene spans approximately 2.5 kb of genomic DNA and consists of 9 exons. In the promoter region of PHR1, there are two pairs of inverted repeats spanning more than sixty base pairs. The promoter also contains DNA motifs similar to the GT-1 box or G-box found in many light-inducible gene promoters. EMSA analysis showed that several proteins in Arabidopsis nuclear extract bound to the G-box-like motifs. These results raise the possibility that the Arabidopsis PHRl gene is regulated by transcription factors which interact with these motifs.