Activation of Rab GTPase Sec4 by its GEF Sec2 is required for prospore membrane formation during sporulation in yeast Saccharomyces cerevisiae
Activation of Rab GTPase Sec4 by its GEF Sec2 is required for prospore membrane formation during sporulation in yeast Saccharomyces cerevisiae
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DOI：
10.1093/femsyr/fox095
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发表时间：
2018-02-01
影响因子：
3.2
通讯作者：
Irie, Kenji
中科院分区：
文献类型：
--
作者：
Suda, Yasuyuki;Tachikawa, Hiroyuki;Irie, Kenji
Sec 2激活Sec 4 Rab GT3作为鸟嘌呤核苷酸交换因子，用于募集下游效应物，以促进高尔基体后囊泡在质膜处的束缚和融合。在芽殖酵母减数分裂和孢子形成过程中，高尔基体后囊泡被运送到纺锤体极体（SPB）并融合，形成一个新的膜，称为原孢子膜。先前的研究已经揭示了被称为减数分裂外斑（MOP）的SPB外表面在高尔基体后囊泡的对接和融合中的作用。然而，上游分子机制后高尔基体泡状融合，促进原孢子膜的形成仍然是谜。在这里，我们证明，GTP交换因子Sec 4，Sec 2，参与形成的原孢子膜。一个条件突变体，其中SEC 2的表达是关闭在孢子形成过程中表现出孢子形成缺陷。Sec 2的失活导致沿着原孢子膜的Sec 4靶向缺陷，从而导致下游效应物和货物蛋白对原孢子膜的靶向不足。这些结果表明，Sec 4的Sec 2激活所需的有效供应后高尔基体囊泡的原孢子膜，从而为原孢子膜的形成/延伸和随后的沉积孢子壁材料。
Sec2 activates Sec4 Rab GTPase as a guanine nucleotide exchange factor for the recruitment of downstream effectors to facilitate tethering and fusion of post-Golgi vesicles at the plasma membrane. During the meiosis and sporulation of budding yeast, post-Golgi vesicles are transported to and fused at the spindle pole body (SPB) to form a de novo membrane, called the prospore membrane. Previous studies have revealed the role of the SPB outer surface called the meiotic outer plaque (MOP) in docking and fusion of post-Golgi vesicles. However, the upstream molecular machinery for post-Golgi vesicular fusion that facilitates prospore membrane formation remains enigmatic.Here, we demonstrate that the GTP exchange factor for Sec4, Sec2, participates in the formation of the prospore membrane. A conditional mutant in which the SEC2 expression is shut off during sporulation showed sporulation defects. Inactivation of Sec2 caused Sec4 targeting defects along the prospore membranes, thereby causing insufficient targeting of downstream effectors and cargo proteins to the prospore membrane. These results suggest that the activation of Sec4 by Sec2 is required for the efficient supply of post-Golgi vesicles to the prospore membrane and thus for prospore membrane formation/extension and subsequent deposition of spore wall materials.