Schapire Arnaldo L, Voigt Boris, Jasik Jan, Rosado Abel, Lopez-Cobollo Rosa, Menzel Diedrik, Salinas Julio, Mancuso Stefano, Valpuesta Victoriano, Baluska Frantisek, Botella Miguel A
Departamento de Biología Molecular y Bioquímica, Universidad de Málaga, 29071 Málaga, Spain.
Plant Cell. 2008 Dec;20(12):3374-88. doi: 10.1105/tpc.108.063859. Epub 2008 Dec 16.
Plasma membrane repair in animal cells uses synaptotagmin 7, a Ca(2+)-activated membrane fusion protein that mediates delivery of intracellular membranes to wound sites by a mechanism resembling neuronal Ca(2+)-regulated exocytosis. Here, we show that loss of function of the homologous Arabidopsis thaliana Synaptotagmin 1 protein (SYT1) reduces the viability of cells as a consequence of a decrease in the integrity of the plasma membrane. This reduced integrity is enhanced in the syt1-2 null mutant in conditions of osmotic stress likely caused by a defective plasma membrane repair. Consistent with a role in plasma membrane repair, SYT1 is ubiquitously expressed, is located at the plasma membrane, and shares all domains characteristic of animal synaptotagmins (i.e., an N terminus-transmembrane domain and a cytoplasmic region containing two C2 domains with phospholipid binding activities). Our analyses support that membrane trafficking mediated by SYT1 is important for plasma membrane integrity and plant fitness.
动物细胞中的质膜修复利用突触结合蛋白7，这是一种Ca(2+)激活的膜融合蛋白，通过类似于神经元Ca(2+)调节的胞吐作用机制，介导细胞内膜向伤口部位的运输。在这里，我们表明，同源拟南芥突触结合蛋白1（SYT1）功能丧失会导致细胞膜完整性下降，从而降低细胞活力。在可能由有缺陷的质膜修复引起的渗透胁迫条件下，syt1-2缺失突变体的这种完整性降低更为明显。与在质膜修复中的作用一致，SYT1在植物中普遍表达，位于质膜上，并具有动物突触结合蛋白的所有特征结构域（即N端跨膜结构域和包含两个具有磷脂结合活性的C2结构域的胞质区域）。我们的分析支持由SYT1介导的膜运输对质膜完整性和植物适应性很重要。
