Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, CMC, Université de Strasbourg CNRS, Strasbourg, France.
University of Strasbourg Institute for Advanced Studies (USIAS), Strasbourg, France.
FEBS Lett. 2020 Oct;594(20):3356-3362. doi: 10.1002/1873-3468.13907. Epub 2020 Aug 30.
The monoclonal antibody 4B1 binds to a conformational epitope on the periplasmic side of lactose permease (LacY) of Escherichia coli and inhibits H /lactose symport and lactose efflux under nonenergized conditions. At the same time, ligand binding and translocation reactions that do not involve net H translocation remain unaffected by 4B1. In this study, surface-enhanced infrared absorption spectroscopy applied to the immobilized LacY was used to study the pH-dependent changes in LacY and to access in situ the effect of the 4B1 antibody on the pK of Glu325, the primary functional H -binding site in LacY. A small shift of the pK value from 10.5 to 9.5 was identified that can be corroborated with the inactivation of LacY upon 4B1 binding.
单克隆抗体 4B1 与大肠杆菌乳糖通透酶 (LacY) 周质侧的构象表位结合，并在非能量条件下抑制 H+/乳糖共转运和乳糖外排。同时，不涉及净 H 转运的配体结合和易位反应不受 4B1 的影响。在这项研究中，应用于固定化 LacY 的表面增强红外吸收光谱用于研究 LacY 的 pH 依赖性变化，并原位研究 4B1 抗体对 LacY 中主要功能 H 结合位点 Glu325 的 pK 值的影响。鉴定出 pK 值从 10.5 到 9.5 的小偏移，这可以与 4B1 结合导致 LacY 失活相印证。
