From the State Key Laboratory of Bio-membrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua-Peking Center for Life Sciences, and.
Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua-Peking Center for Life Sciences, and Ministry of Education Key Laboratory of Protein Science, Tsinghua University, Beijing 100084, China.
J Biol Chem. 2014 Nov 7;289(45):31503-12. doi: 10.1074/jbc.M114.575472. Epub 2014 Sep 17.
Pentatricopeptide repeat (PPR) proteins, particularly abundant in plastids and mitochrondria of angiosperms, include a large number of sequence-specific RNA binding proteins that are involved in diverse aspects of organelle RNA metabolisms. PPR proteins contain multiple tandom repeats, and each repeat can specifically recognize a RNA base through residues 2, 5, and 35 in a modular fashion. The crystal structure of PPR10 from maize chloroplast exhibits dimeric existence both in the absence and presence of the 18-nucleotide psaJ RNA element. However, previous biochemical analysis suggested a monomeric shift of PPR10 upon RNA binding. In this report, we show that the amino-terminal segments of PPR10 determine the dimerization state of PPR10. A single amino acid alteration of cysteine to serine within repeat 10 of PPR10 further drives dimerization of PPR10. The biochemical elucidation of the determinants for PPR10 dimerization may provide an important foundation to understand the working mechanisms of PPR proteins underlying their diverse physiological functions.
五肽重复（PPR）蛋白，特别是在被子植物的质体和线粒体中丰富存在，包括大量涉及细胞器 RNA 代谢的各个方面的序列特异性 RNA 结合蛋白。PPR 蛋白包含多个串联重复，每个重复可以通过模块化方式特异性识别 RNA 碱基，通过残基 2、5 和 35。来自玉米叶绿体的 PPR10 的晶体结构显示，在不存在和存在 18 个核苷酸的 psaJ RNA 元件的情况下，都以二聚体形式存在。然而，以前的生化分析表明，PPR10 在 RNA 结合时会发生单体转移。在本报告中，我们表明 PPR10 的氨基末端片段决定了 PPR10 的二聚体状态。在 PPR10 的重复 10 中，将半胱氨酸改变为丝氨酸的单个氨基酸改变进一步驱动 PPR10 的二聚化。对 PPR10 二聚化决定因素的生化阐明可能为理解 PPR 蛋白在其多种生理功能下的工作机制提供重要基础。
