Lipid determinants of endocytosis and exocytosis in budding yeast
Lipid determinants of endocytosis and exocytosis in budding yeast
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DOI：
10.1016/j.bbalip.2019.03.007
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发表时间：
2019-07-01
影响因子：
4.8
通讯作者：
Bertl，Adam
中科院分区：
文献类型：
--
作者：
Degreif，Daniel;Cucu，Bayram;Bertl，Adam
细胞保持膜的物理化学特性，以便允许膜相关细胞过程的适当功能，例如内吞作用和胞吐作用。为了研究膜特性和生物过程之间的相互作用，我们应用脂质工程方法，允许系统操纵脂肪酸不饱和度和甾醇生物合成，膜流动性的主要调节剂。结合电生理学膜电容测量，我们能够研究的依赖性的膜脂质组成的酿酒酵母的内分泌和外分泌活性在体内。我们发现，细胞的总麦角固醇含量的强烈下降导致囊泡分裂（内吞作用）的频率严重降低，而胞吐活性基本上不受影响。相比之下，增加脂质饱和度降低内吞和胞吐活性，前者受到更严重的影响。我们能够相关的内吞/外吞频率（fendo/fexo）的比例下降后脂质扰动与酵母原生质体的生长，这是基于一个表面扩大导致净过量的外吞流量。使用网格蛋白缺陷突变体的实验证实了内吞活性降低和完整壁细胞大小增加以及原生质体生长加速之间的相关性。这些数据表明，脂质组合物是紧密联系在一起的膜运输酵母细胞，并建议，内吞作用是特别依赖于脂质定义的细胞膜的性能。
Cells maintain physicochemical characteristics of membranes in order to allow for proper function of membrane-associated cellular processes, such as endocytosis and exocytosis. To investigate the interplay between membrane properties and biological processes, we applied lipid engineering approaches that allowed for systematic manipulation of fatty acid unsaturation and sterol biosynthesis, the main regulators of membrane fluidity. In combination with electrophysiological membrane capacitance measurements, we were able to study the dependence of the endo- and exocytic activity of Saccharomyces cerevisiae on membrane lipid composition in vivo. We found that a strong decrease in the cell's total ergosterol content leads to a severely reduced frequency of vesicle fission (endocytosis), whereas the exocytic activity remained largely unaffected. In contrast, increased lipid saturation lowered both endocytic and the exocytic activity, with the former being more severely affected. We were able to correlate the decreased ratio of endocytic/exocytic frequencies (fendo/fexo) upon lipid perturbation with the growth of yeast protoplasts, which is based on a surface enlargement resulting from a net excess of exocytic over endocytic flux. Experiments using clathrin-deficient mutants confirm a correlation between reduced endocytic activity and increased size of intact walled cells, as well as accelerated protoplast growth. These data show that lipid composition is intimately tied to membrane trafficking in yeast cells and suggest that endocytosis is particularly dependent on the lipid-defined properties of cell membrane.