National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
J Integr Plant Biol. 2012 Feb;54(2):87-98. doi: 10.1111/j.1744-7909.2012.01094.x.
Gene expression in chloroplasts is regulated by many nuclear-encoded proteins. In this study, we isolated a rice (Oryza sativa subsp. japonica) mutant osotp51 with significant reduction in photosystem I (PSI). The osotp51 is extremely sensitive to light and accumulates a higher level of reactive oxygen species. Its leaves are almost albino when grown at 40 μmol photons/m(2) per s. However, grown at 4 μmol photons/m(2) per s, osotp51 has a similar phenotype to the wild-type. 77K chlorophyll fluorescence analysis showed a blue shift in the highest peak emission from PSI in osotp51. In addition, the level of PSI and PSII dimer is dramatically reduced in osotp51. OSOTP 51 encodes a pentatricopeptide repeats protein, homologous to organelle transcript processing 51 in Arabidopsis. Loss-of-function OSOTP51 affects intron splicing of a number of plastid genes, particularly the ycf3 coding a protein involved in the assembly of PSI complex. OSOTP51 is functionally conserved in higher plants. The mutation of osotp51 indirectly leads to a widespread change in the structure and functions of PSI, results in severe photoinhibition, and finally dies, even when grown under very low light intensity.
叶绿体中的基因表达受许多核编码蛋白调控。在这项研究中，我们分离到一个水稻（Oryza sativa subsp. japonica）突变体 osotp51，其光合作用 I（PSI）显著减少。osotp51 对光极为敏感，会积累更高水平的活性氧。在 40 μmol 光子/m²/s 的光强下生长时，其叶片几乎呈白化状。然而，在 4 μmol 光子/m²/s 的光强下生长时，osotp51 的表型与野生型相似。77K 叶绿素荧光分析表明，osotp51 中 PSI 的最高峰值发射发生蓝移。此外，PSI 和 PSII 二聚体的水平在 osotp51 中显著降低。OSOTP 51 编码一种五肽重复蛋白，与拟南芥的细胞器转录加工 51 同源。功能丧失的 OSOTP51 影响许多质体基因的内含子剪接，特别是编码参与 PSI 复合物组装的蛋白的 ycf3 基因。OSOTP51 在高等植物中具有功能保守性。osotp51 的突变会间接导致 PSI 的结构和功能发生广泛变化，导致严重的光抑制，最终死亡，即使在非常低的光强下生长也是如此。
