Kolokouris Dimitrios, Kalenderoglou Iris E, Duncan Anna L, Corey Robin A, Sansom Mark S P, Kolocouris Antonios
Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece.
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K.
J Chem Theory Comput. 2025 Jan 28;21(2):912-932. doi: 10.1021/acs.jctc.4c01026. Epub 2024 Nov 4.
The influenza A M2 homotetrameric channel consists of four transmembrane (TM) and four amphipathic helices (AHs). This viral proton channel is suggested to form clusters in the catenoid budding neck areas in raft-like domains of the plasma membrane, resulting in cell membrane scission and viral release. The channel clustering environment is rich in cholesterol. Previous experiments have shown that cholesterol significantly contributes to lipid bilayer undulations in viral buds. However, a clear explanation of membrane curvature from the distribution of cholesterol around the M2TM-AH clusters is lacking. Using coarse-grained molecular dynamics simulations of M2TM-AH in bilayers, we observed that M2 channels form specific, C2-symmetric, clusters with conical shapes driven by the attraction of their AHs. We showed that cholesterol stabilized the formation of M2 channel clusters by filling and bridging the conical gap between M2 channels at specific sites in the N-termini of adjacent channels or via the C-terminal region of TM and AHs, with the latter sites displaying a longer interaction time and higher stability. The potential of mean force calculations showed that when cholesterols occupy the identified interfacial binding sites between two M2 channels, the dimer is stabilized by 11 kJ/mol. This translates to the cholesterol-bound dimer being populated by almost 2 orders of magnitude compared to a dimer lacking cholesterol. We demonstrated that the cholesterol-bridged M2 channels can exert a lateral force on the surrounding membrane to induce the necessary negative Gaussian curvature profile, which permits spontaneous scission of the catenoid membrane neck and leads to viral buds and scission.
甲型流感病毒的M2同四聚体通道由四个跨膜（TM）螺旋和四个两亲性螺旋（AHs）组成。这种病毒质子通道被认为在质膜筏状结构域的链状出芽颈部区域形成簇，从而导致细胞膜分裂和病毒释放。通道聚集的环境富含胆固醇。先前的实验表明，胆固醇对病毒芽中脂质双层的波动有显著贡献。然而，目前尚缺乏从M2TM - AH簇周围胆固醇分布的角度对膜曲率的清晰解释。通过对双层膜中M2TM - AH进行粗粒度分子动力学模拟，我们观察到M2通道通过其AHs的吸引力形成特定的、C2对称的、圆锥形簇。我们发现，胆固醇通过填充和桥接相邻通道N端特定位点的M2通道之间的锥形间隙，或通过TM和AHs的C端区域，稳定了M2通道簇的形成，其中后一个位点显示出更长的相互作用时间和更高的稳定性。平均力势计算表明，当胆固醇占据两个M2通道之间确定的界面结合位点时，二聚体的稳定性增加11 kJ/mol。这意味着与缺乏胆固醇的二聚体相比，结合胆固醇的二聚体数量增加了近两个数量级。我们证明，胆固醇桥接的M2通道可以对周围膜施加侧向力，以诱导必要的负高斯曲率分布，从而允许链状膜颈部自发分裂，导致病毒芽的形成和分裂。
