Structural and Functional Studies of Human Serine Palmitoyltransferase Complexes

项目总结 鞘磷脂不仅是真核膜的重要结构成分，而且还具有如下功能： 信号分子，并调节许多生物过程。鞘磷脂代谢缺陷通常是 与癌症和神经退行性疾病有关。尽管生物活性鞘脂很重要， 它们的生物发生和稳态的分子机制仍然知之甚少。在人类中，第一个和 鞘脂生物合成的限速步骤是由丝氨酸棕榈酰转移酶复合体催化的，该复合体 由催化成分SPTLCs和调节成分ssSPT和ORMDL组成。这个关键酶 Complex还感应细胞鞘脂水平以相应地调整鞘脂的产生，使其成为一种 关键反馈调节剂在维持鞘脂动态平衡中的作用。人类复合体中的突变导致 遗传性感觉神经病和早发性肌萎缩侧索硬化症。然而，这一机制和 对该建筑群的监管尚不清楚。我们建议阐明1)底物识别和催化 复合体的反应，2)调节成分的作用，以及3)鞘磷脂的感觉和反馈 机制。为了实现这些目标，我们将结合高分辨率结构生物学、生物化学和 生物物理学：提供对鞘脂生物发生和动态平衡的结构性和机械性见解 由丝氨酸棕榈酰转移酶复合体控制。我们建议的研究将极大地促进我们的 通过揭示鞘脂中一个重要步骤的分子基础来理解鞘脂生物学 神经鞘脂的生物发生和动态平衡机制。

PROJECT SUMMARY Sphingolipids not only are essential structural components of eukaryotic membranes, but also function as signaling molecules and mediate many biological processes. Defects in sphingolipid metabolism are often associated with cancers and neurodegenerative diseases. Despite the importance of bioactive sphingolipids, molecular mechanisms of their biogenesis and homeostasis remain poorly understood. In humans, the first and rate-limiting step of sphingolipid biosynthesis is catalyzed by the serine palmitoyltransferase complex, which consists of catalytic component SPTLCs and regulatory components ssSPT and ORMDL. This key enzyme complex also senses cellular sphingolipid levels to adjust sphingolipid production accordingly, making it a critical feedback regulator in maintaining sphingolipid homeostasis. Human mutations in the complex lead to hereditary sensory neuropathy and early-onset amyotrophic lateral sclerosis. However, the mechanism and regulation of the complex are unclear. We propose to elucidate 1) the substrate recognition and catalytic reaction of the complex, 2) the role of regulatory components, and 3) the sphingolipid-sensing and feedback mechanism. To accomplish these aims, we will combine high-resolution structural biology, biochemistry, and biophysics to provide structural and mechanistic insights into sphingolipid biogenesis and homeostasis governed by the serine palmitoyltransferase complex. Our proposed studies will greatly advance our understanding of sphingolipid biology by uncovering the molecular basis of an essential step in sphingolipid biogenesis and a mechanism of sphingolipid homeostasis.