Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan.
FEBS Lett. 2011 Nov 16;585(22):3533-7. doi: 10.1016/j.febslet.2011.10.015. Epub 2011 Oct 19.
ATP-binding cassette (ABC) transporters couple hydrolysis of ATP with vectorial transport across the cell membrane. We have reconstituted ABC transporter MsbA in nanodiscs of various sizes and lipid compositions to test whether ATPase activity is modulated by the properties of the bilayer. ATP hydrolysis rates, Michaelis-Menten parameters, and dissociation constants of substrate analog ATP-γ-S demonstrated that physicochemical properties of the bilayer modulated binding and ATPase activity. This is remarkable when considering that the catalytic unit is located ~50Å from the transmembrane region. Our results validated the use of nanodiscs as an effective tool to reconstitute MsbA in an active catalytic state, and highlighted the close relationship between otherwise distant transmembrane and ATPase modules.
三磷酸腺苷结合盒(ABC)转运蛋白将三磷酸腺苷的水解与跨细胞膜的载体运输偶联。我们已经将 ABC 转运蛋白 MsbA 重新组装到各种大小和脂质组成的纳米盘中,以测试 ATP 酶活性是否受双层膜性质的调节。ATP 水解速率、米氏常数参数和底物类似物 ATP-γ-S 的解离常数表明,双层膜的物理化学性质调节了结合和 ATP 酶活性。当考虑到催化单元位于跨膜区域约 50Å 处时,这是非常显著的。我们的结果验证了使用纳米盘作为将 MsbA 重组为有效催化状态的有效工具,并强调了原本相隔甚远的跨膜和 ATP 酶模块之间的密切关系。