Molecular mechanisms of import to nuclei, mitochondria, and chloroplast, and UVB resistance in rice.

环丁烷嘧啶二聚体（CPD）光裂合酶是植物修复CPD的主要途径，而CPD光裂合酶又是决定植物对UVB敏感性的关键因子。我们发现，CPD光解酶，这是由一个单拷贝基因编码的核基因组中，不仅表达和靶向细胞核，但也线粒体和叶绿体。为了阐明水稻各细胞器导入的分子机制，进行了亚细胞定位分析。我们发现391 - 401和487 - 489位氨基酸残基分别是转运到线粒体和细胞核的功能性靶向信号。结果表明，水稻可能已经进化出一种CPD光裂合酶，该酶在所有三种含有DNA的细胞器中发挥作用，以保护细胞免受UVB辐射的有害影响。

Cyclobutane pyrimidine dimer (CPD)photolyase is major pathway for repairing CPD in plant, and CPD photolyase is a crucial factor for determining UVB sensitivity in plants. We found that CPD photolyase, which is encoded by a single-copy gene in the nuclear genome, is expressed and targeted not only to nuclei but also to mitochondria and chloroplasts. To clarify the molecular mechanisms of import to each organelle in rice, the subcellular localization analyses were performed. We found that the amino acids residues from 391 to 401 and from 487 to 489 are functional targeting signal for transport into mitochondria and nuclei, respectively. The results indicate that rice may have evolved a CPD photolyase that functions in all three organelles that contain DNA to protect cells from the harmful effects of UVB radiation.