Braza Mac Kevin E, Dennis Edward A, Amaro Rommie E
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, United States.
J Phys Chem Lett. 2025 Jun 19;16(24):6059-6065. doi: 10.1021/acs.jpclett.5c00860. Epub 2025 Jun 9.
Cytosolic phospholipase A (cPLA) associates with membranes, where it hydrolyzes phospholipids containing arachidonic acid to initiate an inflammatory cascade. All-atom molecular dynamics simulations were employed to understand the activation process when cPLA associates with the endoplasmic reticulum (ER) membrane of macrophages, where it acts. We found that membrane association causes the lid region of cPLA to undergo a closed-to-open state transition that is accompanied by the sideways movement of loop 495-540, allowing the exposure of a cluster of lysine residues (K488, K541, K543, and K544), which are known to bind allosteric activator PIP from the membrane. The active site of the open form of cPLA, containing catalytic dyad residues S228 and D549, exhibited a 3-fold larger cavity than the closed form of cPLA in aqueous solution. These findings provide mechanistic insight into how cPLA-ER membrane association promotes major transitions between conformational states critical to allosteric activation and enzymatic phospholipid hydrolysis.
胞质磷脂酶A（cPLA）与膜结合，在膜上它水解含花生四烯酸的磷脂以启动炎症级联反应。我们采用全原子分子动力学模拟来理解cPLA与它发挥作用的巨噬细胞内质网（ER）膜结合时的激活过程。我们发现膜结合导致cPLA的盖子区域从关闭状态转变为开放状态，同时495 - 540环发生侧向移动，使得一簇赖氨酸残基（K488、K541、K543和K544）暴露出来，已知这些残基可结合来自膜的变构激活剂PIP。在水溶液中，cPLA开放形式的活性位点包含催化二元残基S228和D549，其空腔比cPLA关闭形式的空腔大3倍。这些发现为cPLA - ER膜结合如何促进对变构激活和酶促磷脂水解至关重要的构象状态之间的主要转变提供了机制上的见解。
