Department of Functional Organization of Biomembranes, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Department of Microbiology and Immunology, School of Medicine, Stony Brook Universitygrid.36425.36, Stony Brook, New York, USA.
Microbiol Spectr. 2022 Aug 31;10(4):e0196122. doi: 10.1128/spectrum.01961-22. Epub 2022 Jun 27.
Sphingolipids are essential building blocks of eukaryotic membranes and important signaling molecules that are regulated tightly in response to environmental and physiological inputs. While their biosynthetic pathway has been well-described, the mechanisms that facilitate the perception of sphingolipid levels at the plasma membrane remain to be uncovered. In Saccharomyces cerevisiae, the Nce102 protein has been proposed to function as a sphingolipid sensor as it changes its plasma membrane distribution in response to sphingolipid biosynthesis inhibition. We show that Nce102 redistributes specifically in regions of increased sphingolipid demand, e.g., membranes of nascent buds. Furthermore, we report that the production of Nce102 increases following sphingolipid biosynthesis inhibition and that Nce102 is internalized when excess sphingolipid precursors are supplied. This finding suggests that the total amount of Nce102 in the plasma membrane is a measure of the current need for sphingolipids, whereas its local distribution marks sites of high sphingolipid demand. The physiological role of Nce102 in the regulation of sphingolipid synthesis is demonstrated by mass spectrometry analysis showing reduced levels of hydroxylated complex sphingolipids in response to heat stress in the Δ deletion mutant. We also demonstrate that Nce102 behaves analogously in the widespread human fungal pathogen Candida albicans, suggesting a conserved principle of local sphingolipid control across species. Microorganisms are challenged constantly by their rapidly changing environment. To survive, they have developed diverse mechanisms to quickly perceive stressful situations and adapt to them appropriately. The primary site of both stress sensing and adaptation is the plasma membrane. We identified the yeast protein Nce102 as a marker of local sphingolipid levels and fluidity in the plasma membrane. Nce102 is an important structural and functional component of the membrane compartment Can1 (MCC), a plasma membrane microdomain stabilized by a large cytosolic hemitubular protein scaffold, the eisosome. The MCC/eisosomes are widely conserved among fungi and unicellular algae. To determine if Nce102 carries out similar functions in other organisms, we analyzed the human fungal pathogen Candida albicans and found that Nce102 responds to sphingolipid levels also in this organism, which has potential applications for the development of novel therapeutic approaches. The presented study represents a valuable model for how organisms regulate plasma membrane sphingolipids.
鞘脂是真核细胞膜的基本组成部分，也是重要的信号分子，它们可以根据环境和生理输入进行严格调节。虽然它们的生物合成途径已经得到很好的描述，但促进质膜中鞘脂水平感知的机制仍有待发现。在酿酒酵母中，Nce102 蛋白被认为是一种鞘脂传感器，因为它会响应鞘脂生物合成抑制而改变其在质膜中的分布。我们发现，Nce102 会专门在鞘脂需求增加的区域重新分布，例如新生芽的膜。此外，我们报告说，在抑制鞘脂生物合成后，Nce102 的产量会增加，并且当供应过量的鞘脂前体时，Nce102 会被内化。这一发现表明，质膜中 Nce102 的总量是当前对鞘脂需求的衡量标准，而其局部分布则标志着鞘脂需求高的部位。质谱分析显示，在Δ缺失突变体中，鞘脂合成受到热应激的影响，羟基化复杂鞘脂的水平降低，这证明了 Nce102 在调节鞘脂合成中的生理作用。我们还证明，Nce102 在广泛分布的人类真菌病原体白色念珠菌中表现类似，这表明在不同物种中存在保守的局部鞘脂控制原则。微生物不断受到其快速变化的环境的挑战。为了生存，它们已经开发出多种机制来快速感知压力情况并适当地适应它们。应激感应和适应的主要部位是质膜。我们将酵母蛋白 Nce102 鉴定为质膜中局部鞘脂水平和流动性的标志物。Nce102 是膜隔室 Can1（MCC）的重要结构和功能组成部分，MCC 是由一个大型胞质半管状蛋白支架（即 eisosome）稳定的质膜微区。MCC/eisosomes 在真菌和单细胞藻类中广泛保守。为了确定 Nce102 是否在其他生物体中执行类似的功能，我们分析了人类真菌病原体白色念珠菌，并发现 Nce102 也对这种生物体中的鞘脂水平做出反应，这为开发新的治疗方法提供了潜在的应用。本研究为生物体如何调节质膜鞘脂提供了一个有价值的模型。
