Department of Chemistry, King's College London, 7 Trinity Street, London, SE1 1DB, UK.
Center for Biophysics and Quantitative Biology, Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign 405N. Mathews Ave., Urbana, Illinois, 61801, USA.
Nat Commun. 2018 Oct 8;9(1):4151. doi: 10.1038/s41467-018-06704-1.
Secondary transporters undergo structural rearrangements to catalyze substrate translocation across the cell membrane - yet how such conformational changes happen within a lipid environment remains poorly understood. Here, we combine hydrogen-deuterium exchange mass spectrometry (HDX-MS) with molecular dynamics (MD) simulations to understand how lipids regulate the conformational dynamics of secondary transporters at the molecular level. Using the homologous transporters XylE, LacY and GlpT from Escherichia coli as model systems, we discover that conserved networks of charged residues act as molecular switches that drive the conformational transition between different states. We reveal that these molecular switches are regulated by interactions with surrounding phospholipids and show that phosphatidylethanolamine interferes with the formation of the conserved networks and favors an inward-facing state. Overall, this work provides insights into the importance of lipids in shaping the conformational landscape of an important class of transporters.
次级转运蛋白会发生结构重排，以催化跨细胞膜的底物转运——然而，在脂质环境中，这种构象变化是如何发生的，目前仍知之甚少。在这里，我们将氢氘交换质谱（HDX-MS）与分子动力学（MD）模拟相结合，从分子水平上了解脂质如何调节次级转运蛋白的构象动力学。我们使用大肠杆菌中的同源转运蛋白 XylE、LacY 和 GlpT 作为模型系统，发现带电荷残基的保守网络充当分子开关，驱动不同状态之间的构象转变。我们揭示了这些分子开关受到与周围磷脂相互作用的调节，并表明磷脂酰乙醇胺会干扰保守网络的形成，并有利于内向构象。总的来说，这项工作深入了解了脂质在塑造一类重要转运蛋白构象景观方面的重要性。
