Dalal Jyoti, Lewis Daniel R, Tietz Olaf, Brown Erica M, Brown Christopher S, Palme Klaus, Muday Gloria K, Sederoff Heike W
Dept. of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7621, United States.
Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109, United States.
J Plant Physiol. 2016 Jun 1;196-197:28-40. doi: 10.1016/j.jplph.2016.03.011. Epub 2016 Mar 24.
The gravitropic bending in plant roots is caused by asymmetric cell elongation. This requires an asymmetric increase in cell surface and therefore plasma membrane components such as lipids, sterols, and membrane proteins. We have identified an early gravity-regulated protein in Arabidopsis thaliana root apices that binds stigmasterol and phosphoethanolamines. This root-specific protein interacts with the membrane transport protein synaptotagmin-1 and was therefore named InteractoR Of SYnaptotagmin1 (ROSY1). While interactions between ML-domain proteins with membrane transport proteins and their impact have been reported from animal cell systems, this is the first report of such an interaction in a plant system. Homozygous mutants of ROSY1 exhibit decreased basipetal auxin transport, a faster root gravitropic response, and an increase in salt stress tolerance. Our results suggest that ROSY1 plays a role in root gravitropism, possibly by facilitating membrane trafficking and asymmetric cell elongation via its interaction with synaptotagmin-1.
植物根的向重力性弯曲是由不对称细胞伸长引起的。这需要细胞表面以及因此脂质、甾醇和膜蛋白等质膜成分的不对称增加。我们在拟南芥根尖中鉴定出一种早期重力调节蛋白，它能结合豆甾醇和磷酸乙醇胺。这种根特异性蛋白与膜转运蛋白突触结合蛋白-1相互作用，因此被命名为突触结合蛋白1相互作用因子（ROSY1）。虽然在动物细胞系统中已报道了ML结构域蛋白与膜转运蛋白之间的相互作用及其影响，但这是植物系统中此类相互作用的首次报道。ROSY1的纯合突变体表现出向基生长素运输减少、根向重力性反应加快以及盐胁迫耐受性增加。我们的结果表明，ROSY1可能通过与突触结合蛋白-1相互作用促进膜运输和不对称细胞伸长，从而在根向重力性中发挥作用。
