title: A proposed time-resolved X-ray scattering approach to track local and global conformational changes in membrane transport proteins.
abstract: Time-resolved X-ray scattering has emerged as a powerful technique for studying the rapid structural dynamics of small molecules in solution. Membrane-protein-catalyzed transport processes frequently couple large-scale conformational changes of the transporter with local structural changes perturbing the uptake and release of the transported substrate. Using light-driven halide ion transport catalyzed by halorhodopsin as a model system, we combine molecular dynamics simulations with X-ray scattering calculations to demonstrate how small-molecule time-resolved X-ray scattering can be extended to the study of membrane transport processes. In particular, by introducing strongly scattering atoms to label specific positions within the protein and substrate, the technique of time-resolved wide-angle X-ray scattering can reveal both local and global conformational changes. This approach simultaneously enables the direct visualization of global rearrangements and substrate movement, crucial concepts that underpin the alternating access paradigm for membrane transport proteins.
authors.affiliation: Department of Chemical and Biological Engineering, Molecular Biotechnology, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Andersson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Vincent
authors.forename: David
authors.initials: D
authors.lastname: van der Spoel
authors.forename: Jan
authors.initials: J
authors.lastname: Davidsson
authors.forename: Richard
authors.initials: R
authors.lastname: Neutze
mesh_terms: D007700:Kinetics; D026901:Membrane Transport Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008961:Models, Structural; D010777:Photochemistry; D011487:Protein Conformation; D012542:Scattering, Radiation; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D026901:Membrane Transport Proteins