Reconstitution of ORP- mediated lipid exchange coupled to PI4P metabolism

• 成果类型: Article
• 署名作者: Fuggetta, Nicolas; Rigolli, Nicola; Magdeleine, Maud; Hamai, Amazigh; Seminara, Agnese; Drin, Guillaume
• 署名单位: Centre National de la Recherche Scientifique (CNRS); Universite Cote d'Azur; Universite Paris Cite; University of Genoa
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15415
• DOI: 10.1073/pnas.2315493121
• 发表日期: 2024-03-05
• 关键词: phosphatidylinositol 4-kinase; dependent regulation; golgi-complex; proteins; phosphoinositides; 4-phosphate; secretion; binding; phosphatidylserine; cerevisiae

摘要

Oxysterol- binding protein- related proteins (ORPs) play key roles in the distribution of lipids in eukaryotic cells by exchanging sterol or phosphatidylserine for PI4P between the endoplasmic reticulum (ER) and other cell regions. However, it is unclear how their exchange capacity is coupled to PI4P metabolism. To address this question quantitatively, we analyze the activity of a representative ORP, Osh4p, in an ER/Golgi interface reconstituted with ER- and Golgi- mimetic membranes functionalized with PI4P phosphatase Sac1p and phosphatidylinositol (PI) 4- kinase, respectively. Using real - time assays, we demonstrate that upon adenosine triphosphate (ATP) addition, Osh4p creates a sterol gradient between these membranes, relying on the spatially distant synthesis and hydrolysis of PI4P, and quantify how much PI4P is needed for this process. Then, we develop a quantitatively accurate kinetic model, validated by our data, and extrapolate this to estimate to what extent PI4P metabolism can drive ORP- mediated sterol transfer in cells. Finally, we show that Sec14p can support PI4P metabolism and Osh4p activity by transferring PI between membranes. This study establishes that PI4P synthesis drives ORP- mediated lipid exchange and that ATP energy is needed to generate intermembrane lipid gradients. Furthermore, it defines to what extent ORPs can distribute lipids in the cell and reassesses the role of PI- transfer proteins in PI4P metabolism.