title: Mapping transiently formed and sparsely populated conformations on a complex energy landscape.
abstract: Determining the structures, kinetics, thermodynamics and mechanisms that underlie conformational exchange processes in proteins remains extremely difficult. Only in favourable cases is it possible to provide atomic-level descriptions of sparsely populated and transiently formed alternative conformations. Here we benchmark the ability of enhanced-sampling molecular dynamics simulations to determine the free energy landscape of the L99A cavity mutant of T4 lysozyme. We find that the simulations capture key properties previously measured by NMR relaxation dispersion methods including the structure of a minor conformation, the kinetics and thermodynamics of conformational exchange, and the effect of mutations. We discover a new tunnel that involves the transient exposure towards the solvent of an internal cavity, and show it to be relevant for ligand escape. Together, our results provide a comprehensive view of the structural landscape of a protein, and point forward to studies of conformational exchange in systems that are less characterized experimentally.
authors.affiliation: Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Yong
authors.identifier: 0000-0001-9156-0377
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Elena
authors.identifier: 0000-0002-7376-5894
authors.initials: E
authors.lastname: Papaleo
authors.affiliation: Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kresten
authors.identifier: 0000-0002-4750-6039
authors.initials: K
authors.lastname: Lindorff-Larsen
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology*; D056004:Molecular Dynamics Simulation; D009113:Muramidase / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D009113:Muramidase
keywords: biochemistry; biophysics; conformational exchange; free energy landscape; kinetics; molecular dynamics; nuclear magnetic resonance; structural biology