Ning Wang, Jiale Xing, Xiaodong Su, Junting Pan, Hui Chen, Lifang Shi, Long Si, Wenqiang Yang, Mei Li
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引用次数: 0
Abstract
Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC-TIC translocon that spans the chloroplast envelope membranes. A motor complex pulls the translocated proteins out of the TOC-TIC complex into the chloroplast stroma by hydrolyzing ATP. The Orf2971-FtsHi complex has been suggested to serve as the ATP-hydrolyzing motor in Chlamydomonas reinhardtii, but little is known about its architecture and assembly. Here, we report the 3.2-Å resolution structure of the Chlamydomonas Orf2971-FtsHi complex. The 20-subunit complex spans the chloroplast inner envelope, with two bulky modules protruding into the intermembrane space and stromal matrix. Six subunits form a hetero-hexamer that potentially provides the pulling force through ATP hydrolysis. The remaining subunits, including potential enzymes/chaperones, likely facilitate the complex assembly and regulate its proper function. Taken together, our results provide the structural foundation for a mechanistic understanding of chloroplast protein translocation.
数以千计的核编码蛋白质通过横跨叶绿体包膜的 TOC-TIC 易位体运输到叶绿体中。一个马达复合物通过水解 ATP 将转运蛋白从 TOC-TIC 复合物中拉出,进入叶绿体基质。Orf2971-FtsHi 复合物被认为是衣藻中的 ATP 水解马达,但人们对其结构和组装知之甚少。在此,我们报告了衣藻 Orf2971-FtsHi 复合物的 3.2 Å 分辨率结构。这个由 20 个亚基组成的复合体横跨叶绿体内包膜,其中两个大模块突出到膜间隙和基质中。六个亚基组成一个异质六聚体,可能通过 ATP 水解提供拉力。其余的亚基,包括潜在的酶/伴侣,可能会促进复合体的组装并调节其正常功能。我们的研究结果为从机理上理解叶绿体蛋白质的转运提供了结构基础。
期刊介绍:
Molecular Plant is dedicated to serving the plant science community by publishing novel and exciting findings with high significance in plant biology. The journal focuses broadly on cellular biology, physiology, biochemistry, molecular biology, genetics, development, plant-microbe interaction, genomics, bioinformatics, and molecular evolution.
Molecular Plant publishes original research articles, reviews, Correspondence, and Spotlights on the most important developments in plant biology.