Related Experiment Video
Updated: Nov 10, 2025
X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Crystal structures of LeuT reveal conformational dynamics in the outward-facing states
Jianjun Fan1, Yang Xiao1, Matthias Quick2
1Department of Integrated Traditional Chinese and Western Medicine, Rare Diseases Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
Abstract:
The neurotransmitter:sodium symporter (NSS) homolog LeuT from Aquifex aeolicus has proven to be a valuable model for studying the transport mechanism of the NSS family. Crystal structures have captured LeuT in key conformations visited during the transport cycle, allowing for the construction of a nearly complete model of transport, with much of the conformational dynamics studied by computational simulations. Here, we report crystal structures of LeuT representing new intermediate conformations between the outward-facing open and occluded states. These structures, combined with binding and accessibility studies, reveal details of conformational dynamics that can follow substrate binding at the central substrate binding site (S1) of LeuT in outward-facing states, suggesting a potential competition for direction between the outward-open and outward-occluded states at this stage during substrate transport. Our structures further support an intimate interplay between the protonation state of Glu290 and binding of Na1 that may ultimately regulate the outward-open-to-occluded transition.
Related Concept Videos
01:22Protein Folding
01:25Protein Folding
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:02Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
02:11Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...