Liu Chen, Mentzelopoulou Andriani, Papagavriil Fotini, Ramachandran Prashanth, Perraki Artemis, Claus Lucas, Barg Sebastian, Dörmann Peter, Jaillais Yvon, Johnen Philipp, Russinova Eugenia, Gizeli Electra, Schaaf Gabriel, Moschou Panagiotis Nikolaou
Department of Biology, University of Crete, Heraklion, Greece.
Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece.
PLoS Biol. 2023 Sep 18;21(9):e3002305. doi: 10.1371/journal.pbio.3002305. eCollection 2023 Sep.
Protein function can be modulated by phase transitions in their material properties, which can range from liquid- to solid-like; yet, the mechanisms that drive these transitions and whether they are important for physiology are still unknown. In the model plant Arabidopsis, we show that developmental robustness is reinforced by phase transitions of the plasma membrane-bound lipid-binding protein SEC14-like. Using imaging, genetics, and in vitro reconstitution experiments, we show that SEC14-like undergoes liquid-like phase separation in the root stem cells. Outside the stem cell niche, SEC14-like associates with the caspase-like protease separase and conserved microtubule motors at unique polar plasma membrane interfaces. In these interfaces, SEC14-like undergoes processing by separase, which promotes its liquid-to-solid transition. This transition is important for root development, as lines expressing an uncleavable SEC14-like variant or mutants of separase and associated microtubule motors show similar developmental phenotypes. Furthermore, the processed and solidified but not the liquid form of SEC14-like interacts with and regulates the polarity of the auxin efflux carrier PINFORMED2. This work demonstrates that robust development can involve liquid-to-solid transitions mediated by proteolysis at unique plasma membrane interfaces.
蛋白质的功能可通过其物质特性的相变来调节，这些相变范围从类似液体到类似固体；然而，驱动这些转变的机制以及它们对生理学是否重要仍然未知。在模式植物拟南芥中，我们发现质膜结合的脂质结合蛋白类SEC14的相变增强了发育稳健性。通过成像、遗传学和体外重建实验，我们表明类SEC14在根干细胞中经历类似液体的相分离。在干细胞龛之外，类SEC14在独特的极性质膜界面处与半胱天冬酶样蛋白酶分离酶和保守的微管马达相关联。在这些界面中，类SEC14被分离酶加工，这促进了其从液体到固体的转变。这种转变对根发育很重要，因为表达不可切割的类SEC14变体或分离酶及相关微管马达突变体的株系表现出相似的发育表型。此外，加工并固化后的类SEC14而非液体形式与生长素外排载体PINFORMED2相互作用并调节其极性。这项工作表明，稳健的发育可能涉及在独特质膜界面处由蛋白水解介导的从液体到固体的转变。
