A pentatricopeptide repeat protein is required for RNA processing of clpP pre-mRNA in moss chloroplasts
A pentatricopeptide repeat protein is required for RNA processing of clpP pre-mRNA in moss chloroplasts
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DOI：
10.1074/jbc.m608034200
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发表时间：
2007-04-06
影响因子：
4.8
通讯作者：
Sugita, Mamoru
中科院分区：
文献类型：
--
作者：
Hattori, Mitsuru;Miyake, Hiroshi;Sugita, Mamoru
五肽重复序列（PPR）蛋白是陆生植物核基因组编码的一个大基因家族。PPR蛋白在细胞器相关功能中发挥重要作用，主要是在质体和线粒体中的RNA加工步骤中。在藓类小立碗藓中，也有一个大的基因家族，但藓类PPR蛋白可能与高等植物的PPR蛋白不同。为了研究质体PPR蛋白的功能，我们已经产生并表征了PPR蛋白基因破坏物。PPR531 - 11破坏的藓类植物表现出异常的表型特征，如显着较小的原丝体菌落，不同的叶绿体形态，和不完整的类囊体膜形成。此外，光系统II的量子产率在破坏苔藓减少。为了进一步研究PPR 531 - 11基因的破坏是否影响叶绿体基因的表达，我们进行了北方印迹和逆转录聚合酶链反应分析。这些分析揭示了PPR 531 - 11在clpP和5'-rps 12之间的基因间RNA切割中以及在clpP前mRNA的剪接中具有作用。Western印迹分析表明，破坏PPR531 - 11导致ClpP，光系统II反应中心蛋白D1，和基质酶，核酮糖二磷酸羧化酶/加氧酶的水平降低。这些减少可能导致原丝体群体的生长严重迟缓。综上所述，我们提出了一个模型，其中PPR531 - 11功能影响ClpP的稳态水平，ClpP调节叶绿体中类囊体膜的形成和维持。这是PPR蛋白控制ClpP蛋白表达水平的第一个证据。
Pentatricopeptide repeat ( PPR) proteins are encoded by the nuclear genome as a large gene family in land plants. PPR proteins play essential roles in organelle-related functions, mostly in RNA-processing steps in plastids and mitochondria. In the moss Physcomitrella patens, there is also a large gene family, but the moss PPR proteins are likely to be divergent from those of higher plants. To investigate the function of plastid PPR proteins, we have generated and characterized a PPR protein gene disruptant of P. patens. The PPR531-11- disrupted mosses displayed abnormal phenotypic characteristics, such as a significantly smaller protonemal colony, different chloroplast morphology, and incomplete thylakoid membrane formation. In addition, the quantum yield of photosystem II was reduced in the disrupted mosses. To further investigate whether disruption of the PPR531-11 gene affects chloroplast gene expression, we performed Northern blot and reverse transcription polymerase chain reaction analyses. These analyses revealed that PPR531-11 has a role in intergenic RNA cleavage between clpP and 5'-rps12 and in the splicing of clpP pre-mRNA. Western blot analysis showed that disruption of PPR531-11 resulted in a reduced level of ClpP, photosystem II reaction center protein D1, and the stromal enzyme, ribulose-bisphosphate carboxylase/oxygenase. These reductions might result in the severely retarded growth of the protonemal colony. Taken together, we propose a model where PPR531-11 function affects the steady-state level of ClpP, which regulates the formation and maintenance of thylakoid membranes in chloroplasts. This is the first evidence of a PPR protein controlling the protein expression level of ClpP.