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 plants. We previously reported that CPD photolyase functions in nuclei, chloroplasts and mitochondria in rice. This result indicates that CPD photolyase, which is encoded by a single-copy gene in the nuclear genome, translocates to chloroplasts, mitochondria, and nuclei. Thus, CPD photolyase is subjected to "triple targeting" in rice cell. However, organelle-targeting sequence of CPD photolyase has not been identified. In this study, in order to the identify the organelle-targeting amino acid sequence, we constructed expression vectors encoding protein chimeras of GFP and C-terminal (amino acids 385-506) rice CPD photolyase. The expression vector was introduced into guard cell of Vicia faba or epidermal cell of onion, and cells were examined by fluorescence microscopy. These analyses showed that the C-terminus of rice CPD photolyase contains a functional targeting sequence for transport into nuclei and mitochondria.
