Cfs1p, a Novel Membrane Protein in the PQ-Loop Family, Is Involved in Phospholipid Flippase Functions in Yeast.
Cfs1p, a Novel Membrane Protein in the PQ-Loop Family, Is Involved in Phospholipid Flippase Functions in Yeast.
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DOI：
10.1534/g3.116.035238
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发表时间：
2017-01-05
期刊：
影响因子：
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通讯作者：
Tanaka K
中科院分区：
文献类型：
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作者：
Yamamoto T;Fujimura-Kamada K;Shioji E;Suzuki R;Tanaka K
4型P型ATPase(P4-ATPase)作为磷脂翻转酶，将磷脂从外质叶转移到脂双层的细胞质小叶，产生并维持磷脂在质膜和内体/高尔基体膜上的不对称分布。酿酒酵母芽胞杆菌有四个异构体翻转酶(Drs2p、Dnf1p、Dnf2p和Dnf3p)和一个单体翻转酶(Neo1p)，它们与CDC50p家族非催化亚基相关。它们已被认为在膜转运途径的囊泡形成中发挥作用，但其详细机制仍有待阐明。在这里，为了寻找与Flppase功能相互作用的新因子，我们筛选了转座子插入突变体，以寻找抑制CDC50Δ突变体中冷敏感生长缺陷的菌株。我们发现了YMR010W的一个突变，该突变编码一种新的保守的膜蛋白，该蛋白属于PQ-loop家族，包括胱氨酸转运蛋白、半胱氨酸氨基转移酶和糖转运蛋白。我们将该基因命名为CFS1(CDC 50抑制因子1)。GFP标记的Cfs1p与Drs2p和Neo1p部分共定位于高尔基体内膜/晚期高尔基体膜。有趣的是，CFS1Δ突变抑制了所有Flippase突变体的生长缺陷。相应地，Flippase突变体的膜转运缺陷也被抑制。这些结果表明，Cfs1p和Flippase在膜转运途径中的作用是拮抗的。生长试验表明，CFS1Δ突变改变了质膜中磷脂酰乙醇胺(PE)结合肽的不对称性，从而评估了对硬霉素的敏感性。因此，Cfs1p可能是一种新的磷脂不对称性调节因子。
Type 4 P-type ATPases (P4-ATPases) function as phospholipid flippases, which translocate phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of the lipid bilayer, to generate and maintain asymmetric distribution of phospholipids at the plasma membrane and endosomal/Golgi membranes. The budding yeast Saccharomyces cerevisiae has four heteromeric flippases (Drs2p, Dnf1p, Dnf2p, and Dnf3p), associated with the Cdc50p family noncatalytic subunit, and one monomeric flippase, Neo1p. They have been suggested to function in vesicle formation in membrane trafficking pathways, but details of their mechanisms remain to be clarified. Here, to search for novel factors that functionally interact with flippases, we screened transposon insertional mutants for strains that suppressed the cold-sensitive growth defect in the cdc50Δ mutant. We identified a mutation of YMR010W encoding a novel conserved membrane protein that belongs to the PQ-loop family including the cystine transporter cystinosin and the SWEET sugar transporters. We named this gene CFS1 (cdc fifty suppressor 1). GFP-tagged Cfs1p was partially colocalized with Drs2p and Neo1p to endosomal/late Golgi membranes. Interestingly, the cfs1Δ mutation suppressed growth defects in all flippase mutants. Accordingly, defects in membrane trafficking in the flippase mutants were also suppressed. These results suggest that Cfs1p and flippases function antagonistically in membrane trafficking pathways. A growth assay to assess sensitivity to duramycin, a phosphatidylethanolamine (PE)-binding peptide, suggested that the cfs1Δ mutation changed PE asymmetry in the plasma membrane. Cfs1p may thus be a novel regulator of phospholipid asymmetry.