Abstract
UVB can damage DNA by causing formation of cyclobutane pyrimidine dimer (CPD). Photoreactivation mediated by enzyme, photolyase, is the major pathway for repairing CPD in plant, and CPD photolyase is a crucial factor for determining UVB sensitivity in rice plant. We previously reported that CPD photolyase functioned in nuclei, chloroplasts and mitochondria in rice. This result means CPD photolyase, which is encoded by a single-copy gene in the nuclear genome, translocates to chloroplasts, mitochondria, and nuclei. To clarify the molecular mechanisms of import to each organelle in rice, the subcellular localization analyses were performed. The C-terminus of rice CPD photolyase [385-506 amino acid regions of CPD photolyase (PHR); 385-506-PHR] contains a functional targeting signal for transport into nuclei and mitochondria. We constructed expression vectors encoding protein chimeras of GFP and partial amino acids of CPD photolyase. We found that the signal of 391-401-PHR-GFP was detected in mitochondria, and three amino acids, 487-489, were functional targeting signal for transport into nuclei.
