Role of septins and the exocyst complex in the function of hydrolytic enzymes responsible for fission yeast cell separation
Role of septins and the exocyst complex in the function of hydrolytic enzymes responsible for fission yeast cell separation
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DOI：
10.1091/mbc.e04-12-1114
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发表时间：
2005-10-01
影响因子：
3.3
通讯作者：
de Aldana, CRV
中科院分区：
文献类型：
--
作者：
Martín-Cuadrado, AB;Morrell, JL;de Aldana, CRV
粟酒裂殖酵母中的细胞分离是通过Eng 1内切-β-1，3-葡聚糖酶和Agn 1内切-α-1，3-葡聚糖酶的协同作用实现的，它们被运输到隔膜并定位到围绕隔膜的环状结构。使用绿色荧光蛋白融合蛋白分析了两种水解酶作为环的正确定位的要求。靶向隔膜需要功能性外囊，因为这两种蛋白质在sec 8 -1或exo 70 Delta突变体中均未能正确定位，这表明Agn 1和Eng 1可能是存在于囊泡中的两种货物蛋白，其在外囊突变体中积累。Septins和Mid 2也是正确形成环所必需的。在他们的缺席，Eng 1和Agn 1被发现在一个盘状结构，跨越隔膜，而不是在一个环。尽管Septin和mid 2 Delta突变体具有细胞分离缺陷，但这些细胞中的隔膜和线性β-1，3-葡聚糖的分布是正常的，这表明Eng 1和Agn 1的错误定位可能是未能有效分离的原因。因此，隔蛋白环的功能之一将是作为水解蛋白定位于中间区域的位置标记。
Cell separation in Schizosaccharomyces pombe is achieved by the concerted action of the Eng1 endo-beta-1,3-glucanase and the Agn1 endo-alpha-1,3-glucanase, which are transported to the septum and localize to a ringlike structure that surrounds the septum. The requirements for the correct localization of both hydrolases as a ring were analyzed using green fluorescent protein fusion proteins. Targeting to the septum required a functional exocyst, because both proteins failed to localize correctly in sec8-1 or exo70 Delta mutants, suggesting that Agn1 and Eng1 might be two of the cargo proteins present in the vesicles that accumulate in exocyst mutants. Septins and Mid2 were also required for correct formation of a ring. In their absence, Eng1 and Agn1 were found in a disklike structure that spanned the septum, rather than in a ring. Even though septin and mid2 Delta mutants have a cell separation defect, the septum and the distribution of linear beta-1,3-glucans were normal in these cells, suggesting that mislocalization of Eng1 and Agn1 might be the reason underlying the failure to separate efficiently. Thus, one of the functions of the septin ring would be to act as a positional marker for the localization of hydrolytic proteins to the medial region.