ARC3 Activation by PARC6 Promotes FtsZ-Ring Remodeling at the Chloroplast Division Site
ARC3 Activation by PARC6 Promotes FtsZ-Ring Remodeling at the Chloroplast Division Site
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DOI：
10.1105/tpc.18.00948
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发表时间：
2019-04-01
期刊：
影响因子：
11.6
通讯作者：
Osteryoung, Katherine W.
中科院分区：
文献类型：
--
作者：
Chen, Cheng;Cao, Lingyan;Osteryoung, Katherine W.
叶绿体分裂是由基质Z环的组装开始的，基质Z环由细胞骨架丝化温度敏感的Z （FtsZ）蛋白组成。中质体z环的定位由叶绿体Min （Minicell）系统控制，该系统抑制z环在除分裂位点外的其他部位的组装。min系统的核心参与者是ftsz组装抑制剂氯质体3的积累和复制（ARC3）。在这里，我们报道了拟南芥（Arabidopsis thaliana）叶绿体中包含两个ARC3库：一个分布在整个基质中，可能完全抑制非分裂位点的z环组装，另一个定位于中间质体环状结构。我们发现ARC3通过ARC6的内膜蛋白PARALOG （PARALOG of ARC6, parac6）被募集到质体的中间。ARC3具有c端膜占领和识别Nexus （MORN）结构域；先前对全长和截断的ARC3进行的酵母双杂交实验表明，MORN结构域介导ARC3- parc6相互作用，但阻止ARC3- ftsz相互作用。通过酵母三杂交实验，我们证明了依赖morn的ARC3- parc6相互作用使全长ARC3能够结合FtsZ。得到的PARC6/ARC3/FtsZ配合物增强了异源体系中Z环重构的动力学。我们的研究结果揭示了MORN结构域在调节蛋白质相互作用中的新功能，即PARC6激活中质体定位的ARC3通过促进z环动力学来促进叶绿体分裂过程中z环的重塑。
Chloroplast division is initiated by assembly of the stromal Z ring, composed of cytoskeletal Filamenting temperature-sensitive Z (FtsZ) proteins. Midplastid Z-ring positioning is governed by the chloroplast Min (Minicell) system, which inhibits Z-ring assembly everywhere except the division site. The central Min-system player is the FtsZ-assembly inhibitor ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3). Here, we report Arabidopsis (Arabidopsis thaliana) chloroplasts contain two pools of ARC3: one distributed throughout the stroma, which presumably fully inhibits Z-ring assembly at nondivision sites, and the other localized to a midplastid ring-like structure. We show that ARC3 is recruited to the middle of the plastid by the inner envelope membrane protein PARALOG OF ARC6 (PARC6). ARC3 bears a C-terminal Membrane Occupation and Recognition Nexus (MORN) domain; previous yeast two-hybrid experiments with full-length and MORN-truncated ARC3 showed the MORN domain mediates ARC3-PARC6 interaction but prevents ARC3-FtsZ interaction. Using yeast three-hybrid experiments, we demonstrate that the MORN-dependent ARC3-PARC6 interaction enables full-length ARC3 to bind FtsZ. The resulting PARC6/ARC3/FtsZ complex enhances the dynamics of Z rings reconstituted in a heterologous system. Our findings lead to a model whereby activation of midplastid-localized ARC3 by PARC6 facilitates Z-ring remodeling during chloroplast division by promoting Z-ring dynamics and reveal a novel function for MORN domains in regulating protein-protein interactions.