The exocytic Rabs Ypt3 and Ypt2 regulate the early step of biogenesis of the spore plasma membrane in fission yeast.
The exocytic Rabs Ypt3 and Ypt2 regulate the early step of biogenesis of the spore plasma membrane in fission yeast.
复制标题
DOI：
10.1091/mbc.e16-03-0162
复制
发表时间：
2016-11-01
影响因子：
3.3
通讯作者：
Nakamura T
中科院分区：
文献类型：
--
作者：
Imada K;Nakamura T
两个Rabs，Ypt 3和Ypt 2，调节高尔基体衍生的分泌囊泡的运输在裂殖酵母中孢子质膜的生物发生中具有关键作用。在孢子形成过程中，Rabs和分泌囊泡重新定位在减数分裂纺锤体极体，在那里孢子质膜形成随后启动。在裂殖酵母孢子形成过程中，在纺锤体极体（SPB）上新形成了一个称为前孢子膜（FSM）的膜室。FSM通过膜囊泡融合扩展，包裹减数分裂产生的子核，并最终成熟为孢子的质膜。虽然许多参与FSM形成的基因已被确定，但其分子机制尚未完全了解。在这里，孢子形成缺陷突变的遗传筛选鉴定了Ypt 3，一种已知在胞吐途径中起作用的Rab-family小GTd 3。ypt 3-ki 8突变体在FSM生物发生的启动和FSM扩增中都表现出缺陷。我们还表明，突变Ypt 2，另一个Rab蛋白，可能在相同的途径作为Ypt 3的功能，妥协的FSM形成的启动。随着减数分裂的进行，GFP-Ypt 3和GFP-Ypt 2都在SPB处观察到，然后重新定位到FSM。它们在SPB的定位先于FSM的形成，并依赖于减数分裂SPB组件Spo 13，一个假定的GDP/GTP交换因子Ypt 2。鉴于Spo 13是启动FSM形成必不可少的，这些结果表明，两个外泌Rab，Ypt 3和Ypt 2，调节启动FSM形成的SPB在演唱会Spo 13。
Two Rabs, Ypt3 and Ypt2, regulating the trafficking of Golgi-derived secretory vesicles have key roles in biogenesis of the spore plasma membrane in fission yeast. During sporulation, the Rabs and secretory vesicles relocalize at the meiotic spindle pole body, where spore plasma membrane formation subsequently initiates. During fission yeast sporulation, a membrane compartment called the forespore membrane (FSM) is newly formed on the spindle pole body (SPB). The FSM expands by membrane vesicle fusion, encapsulates the daughter nucleus resulting from meiosis, and eventually matures into the plasma membrane of the spore. Although many of the genes involved in FSM formation have been identified, its molecular mechanism is not fully understood. Here a genetic screen for sporulation-deficient mutations identified Ypt3, a Rab-family small GTPase known to function in the exocytic pathway. The ypt3-ki8 mutant showed defects in both the initiation of FSM biogenesis and FSM expansion. We also show that a mutation in Ypt2, another Rab protein that may function in the same pathway as Ypt3, compromises the initiation of FSM formation. As meiosis proceeds, both GFP-Ypt3 and GFP-Ypt2 are observed at the SPB and then relocalize to the FSM. Their localizations at the SPB precede FSM formation and depend on the meiotic SPB component Spo13, a putative GDP/GTP exchange factor for Ypt2. Given that Spo13 is essential for initiating FSM formation, these results suggest that two exocytic Rabs, Ypt3 and Ypt2, regulate the initiation of FSM formation on the SPB in concert with Spo13.