Negatively charged phospholipids accelerate the membrane fusion activity of the plant-specific insert domain of an aspartic protease.
Negatively charged phospholipids accelerate the membrane fusion activity of the plant-specific insert domain of an aspartic protease.
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带负电荷的磷脂加速天冬氨酸蛋白酶植物特异性插入结构域的膜融合活性
DOI：
10.1016/j.jbc.2021.101430
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发表时间：
2022-01
期刊：
影响因子：
--
通讯作者：
Wang S
中科院分区：
文献类型：
--
作者：
Zhao X;Ma X;Dupius JH;Qi R;Tian JJ;Chen J;Ou X;Qian Z;Liang D;Wang P;Yada RY;Wang S
各种植物使用抗菌蛋白/多肽来抵抗植物病原体。在马铃薯(Solanum Tuberosum)中，天冬氨酸蛋白酶的植物特异性插入(PSI)结构域通过破坏植物病原质膜来发挥这一作用。然而，PSI选择靶膜的机制尚未阐明。在这里，我们研究了PSI诱导的膜融合，重点研究了脂组成对融合效率的影响。PSI的膜融合涉及一种中间状态，通过这种中间状态，相邻的脂质体共享它们的双层。我们发现，增加带负电荷的磷脂酰丝氨酸(PS)磷脂的浓度大大加速了PSI介导的膜融合。核磁共振数据表明，PS不影响PSI与脂质体的结合，但对PSI与脂质体相互作用的动力学有开创性的影响。在不含PS的脂质体中，PSI发生了显著的运动，而在含PS的脂质体中，这种运动被抑制。分子动力学模拟表明，聚硅氧烷与含PS的膜结合，相对于双层膜的优势角在−31°~30°之间，且更接近膜表面。相反，PSI是可移动的，并且在无PS膜的表面显示出多种拓扑态。综上所述，我们的数据表明，PS脂限制了锚定的PSI的运动，使其更接近膜表面，并有效地连接不同的脂质体以加速融合。由于大多数植物病原体与宿主细胞相比具有更高的负电荷脂类含量，这些结果表明PSI选择性地针对负电荷脂类，这可能是区分病原体和寄主的一种方法。
Various plants use antimicrobial proteins/peptides to resist phytopathogens. In the potato, Solanum tuberosum, the plant-specific insert (PSI) domain of an aspartic protease performs this role by disrupting phytopathogen plasma membranes. However, the mechanism by which PSI selects target membranes has not been elucidated. Here, we studied PSI-induced membrane fusion, focusing on the effects of lipid composition on fusion efficiency. Membrane fusion by the PSI involves an intermediate state whereby adjacent liposomes share their bilayers. We found that increasing the concentration of negatively charged phosphatidylserine (PS) phospholipids substantially accelerated PSI-mediated membrane fusion. NMR data demonstrated that PS did not affect the binding between the PSI and liposomes but had seminal effects on the dynamics of PSI interaction with liposomes. In PS-free liposomes, the PSI underwent significant motion, which was suppressed on PS-contained liposomes. Molecular dynamics simulations showed that the PSI binds to PS-containing membranes with a dominant angle ranging from −31° to 30°, with respect to the bilayer, and is closer to the membrane surfaces. In contrast, PSI is mobile and exhibits multiple topological states on the surface of PS-free membranes. Taken together, our data suggested that PS lipids limit the motion of the anchored PSI, bringing it closer to the membrane surface and efficiently bridging different liposomes to accelerate fusion. As most phytopathogens have a higher content of negatively charged lipids as compared with host cells, these results indicate that the PSI selectively targets negatively charged lipids, which likely represents a way of distinguishing the pathogen from the host.