All-Atom Simulations\nReveal the Effect of Membrane\nComposition on the Signaling of the NKG2A/CD94/HLA‑E Immune\nReceptor Complex

Understanding how membrane composition influences the\ndynamics\nand function of transmembrane proteins is crucial for the comprehensive\nelucidation of cellular signaling mechanisms and the development of\ntargeted therapeutics. In this study, we employed all-atom molecular\ndynamics simulations to investigate the impact of different membrane\ncompositions on the conformational dynamics of the NKG2A/CD94/HLA-E\nimmune receptor complex, a key negative regulator of natural killer\ncell cytotoxic activity. Our results reveal significant variations\nin the behavior of the immune complex structure across five different\nmembrane compositions, which include POPC, POPA, DPPC, and DLPC phospholipids,\nand a mixed POPC/cholesterol system. These variations are particularly\nevident in the intracellular domain of NKG2A, manifested as changes\nin mobility, tyrosine exposure, and interdomain communication. Additionally,\nwe found that a large concentration of negative charge at the surface\nof the POPA-based membrane greatly increased the number of contacts\nwith lipid molecules and significantly decreased the exposure of intracellular\nNKG2A ITIM regions to water molecules, thus likely halting the signal\ntransduction process. Furthermore, the DPPC model with a membrane\npossessing a high transition temperature in a gel-like state became\ncurved, affecting the exposure of one ITIM region. The decreased membrane\nthickness in the DPLC model caused a significant transmembrane domain\ntilt, altering the linker protrusion angle and potentially disrupting\nthe hydrogen bonding network in the extracellular domain. Overall,\nour findings highlight the importance of considering membrane composition\nin the analysis of transmembrane protein dynamics and in the exploration\nof novel strategies for the external modulation of their signaling\npathways.