National Engineering Research Center of Tree Breeding and Ecological Restoration, Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
Proc Natl Acad Sci U S A. 2023 Jan 31;120(5):e2215575120. doi: 10.1073/pnas.2215575120. Epub 2023 Jan 25.
Chloroplast division involves the coordination of protein complexes from the stroma to the cytosol. The Min system of chloroplasts includes multiple stromal proteins that regulate the positioning of the division site. The outer envelope protein PLASTID DIVISION1 (PDV1) was previously reported to recruit the cytosolic chloroplast division protein ACCUMULATION AND REPLICATION OF CHLOROPLAST5 (ARC5). However, we show here that PDV1 is also important for the stability of the inner envelope chloroplast division protein PARALOG OF ARC6 (PARC6), a component of the Min system. We solved the structure of both the C-terminal domain of PARC6 and its complex with the C terminus of PDV1. The formation of an intramolecular disulfide bond within PARC6 under oxidized conditions prevents its interaction with PDV1. Interestingly, this disulfide bond can be reduced by light in planta, thus promoting PDV1-PARC6 interaction and chloroplast division. Interaction with PDV1 can induce the dimerization of PARC6, which is important for chloroplast division. Magnesium ions, whose concentration in chloroplasts increases upon light exposure, also promote the PARC6 dimerization. This study highlights the multilayer regulation of the PDV1-PARC6 interaction as well as chloroplast division.
叶绿体分裂涉及来自基质到细胞质的蛋白质复合物的协调。叶绿体的 Min 系统包括多个调节分裂位点定位的基质蛋白。先前有报道称，质体分裂蛋白 1（PDV1）招募质体分裂蛋白 ACCUMULATION AND REPLICATION OF CHLOROPLAST5（ARC5）。然而，我们在这里表明，PDV1 对于 Min 系统的组成部分，内膜质体分裂蛋白 PARALOG OF ARC6（PARC6）的稳定性也很重要。我们解决了 PARC6 的 C 末端结构域及其与 PDV1 的 C 末端复合物的结构。在氧化条件下，PARC6 内形成的分子内二硫键会阻止其与 PDV1 的相互作用。有趣的是，该二硫键可以在体内被光还原，从而促进 PDV1-PARC6 相互作用和叶绿体分裂。与 PDV1 的相互作用可以诱导 PARC6 的二聚化，这对于叶绿体分裂很重要。镁离子的浓度在暴露于光下时会增加，也促进 PARC6 的二聚化。本研究强调了 PDV1-PARC6 相互作用以及叶绿体分裂的多层调节。
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