Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Massachusetts 01003, USA.
Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst, Massachusetts 01003, USA.
Nat Plants. 2016 Jan 11;2:15197. doi: 10.1038/nplants.2015.197.
Many microbes interact with their hosts across a membrane interface, which is often distinct from existing membranes. Understanding how this interface acquires its identity has significant implications. In the symbiosis between legumes and rhizobia, the symbiosome encases the intracellular bacteria and receives host secretory proteins important for bacterial development. We show that the Medicago truncatula SYNTAXIN 132 (SYP132) gene undergoes alternative cleavage and polyadenylation during transcription, giving rise to two target-membrane soluble NSF attachment protein receptor (t-SNARE) isoforms. One of these isoforms, SYP132A, is induced during the symbiosis, is able to localize to the peribacteroid membrane, and is required for the maturation of symbiosomes into functional forms. The second isoform, SYP132C, has important functions unrelated to symbiosis. The SYP132A sequence is broadly found in flowering plants that form arbuscular mycorrhizal symbiosis, an ancestral mutualism between soil fungi and most land plants. SYP132A silencing severely inhibited arbuscule colonization, indicating that SYP132A is an ancient factor specifying plant-microbe interfaces.
许多微生物通过膜界面与宿主相互作用，而该界面通常与现有膜不同。了解这个界面如何获得其特征具有重要意义。在豆科植物与根瘤菌的共生关系中，共生体包裹着细胞内细菌，并接收对细菌发育很重要的宿主分泌蛋白。我们发现蒺藜苜蓿的肌动蛋白 SYP132（SYP132）基因在转录过程中通过选择性剪接和多聚腺苷酸化产生两种靶膜可溶性 NSF 附着蛋白受体（t-SNARE）同工型。这两种同工型之一的 SYP132A 在共生关系中被诱导产生，能够定位于类周质体膜，并且对于共生体成熟为功能性形式是必需的。第二种同工型 SYP132C 具有与共生无关的重要功能。SYP132A 序列广泛存在于形成丛枝菌根共生关系的开花植物中，这是土壤真菌和大多数陆地植物之间的古老共生关系。SYP132A 的沉默严重抑制了丛枝菌根的定植，表明 SYP132A 是一个古老的因子，决定了植物-微生物界面。
