Defects in structural integrity of ergosterol and the Cdc50p-Drs2p putative phospholipid translocase cause accumulation of endocytic membrances, onto which actin patches are assembled in yeast
Defects in structural integrity of ergosterol and the Cdc50p-Drs2p putative phospholipid translocase cause accumulation of endocytic membrances, onto which actin patches are assembled in yeast
复制标题
DOI：
10.1091/mbc.e05-05-0452
复制
发表时间：
2005-12-01
影响因子：
3.3
通讯作者：
Tanaka, K
中科院分区：
文献类型：
--
作者：
Kishimoto, T;Yamamoto, T;Tanaka, K
膜脂组成的特定变化与肌动蛋白细胞骨架组织、囊泡形成和细胞极性控制有关。Cdc 50 p是内体/trans-Golgi网络隔室中的膜蛋白，是Drs 2 p的非催化亚基，其涉及磷脂跨脂质双层的易位。我们发现cdc 50 Delta突变是合成致死的，其突变影响麦角固醇合成的后期步骤（erg 2至erg 6）。在cdc 50 Δ erg 3 Δ突变体中观察到细胞极性和肌动蛋白组织的缺陷。特别是，肌动蛋白补丁，这是通常发现在皮质网站，组装在细胞内沿着与他们的组装因子，包括Las 17 p，Abp 1 p，和Sla 2 p。外吞SNARE Snc 1 p，这是回收的内吞途径，也在细胞内积累，抑制内吞内化抑制细胞质积累的Las 17 p和Snc 1 p。磷脂不对称性和甾醇结构完整性的同时丧失可能导致能够在细胞质中启动肌动蛋白斑块组装的内吞中间体的积累。
Specific changes in membrane lipid composition are implicated in actin cytoskeletal organization, vesicle formation, and control of cell polarity. Cdc50p, a membrane protein in the endosomal/trans-Golgi network compartments, is a noncatalytic subunit of Drs2p, which is implicated in translocation of phospholipids across lipid bilayers. We found that the cdc50 Delta mutation is synthetically lethal with mutations affecting the late steps of ergosterol synthesis (erg2 to erg6). Defects in cell polarity and actin organization were observed in the cdc50 Delta erg3 Delta mutant. In particular, actin patches, which are normally found at cortical sites, were assembled intracellularly along with their assembly factors, including Las17p, Abp1p, and Sla2p. The exocytic SNARE Snc1p, which is recycled by an endocytic route, was also intracellularly accumulated, and inhibition of endocytic internalization suppressed the cytoplasmic accumulation of both Las17p and Snc1p. Simultaneous loss of both phospholipid asymmetry and sterol structural integrity could lead to accumulation of endocytic intermediates capable of initiating assembly of actin patches in the cytoplasm.