6XWM

Mechanism of substrate release in neurotransmitter:sodium symporters: the structure of LeuT in an inward-facing occluded conformation

Summary for 6XWM

• Entry DOI: 10.2210/pdb6xwm/pdb
• Descriptor: Na(+):neurotransmitter symporter (Snf family), PHENYLALANINE, SODIUM ION, ... (4 entities in total)
• Functional Keywords: neurotransmitter:sodium symporters (nss), membrane protein
• Biological source: Aquifex aeolicus VF5
• Total number of polymer chains: 2
• Total formula weight: 116346.96

Authors

Boesen, T.,Nissen, P.,Gotfryd, K.,Loland, C.J.,Gether, U. (deposition date: 2020-01-24, release date: 2020-05-06, Last modification date: 2024-01-24)

Primary citation

Gotfryd, K.,Boesen, T.,Mortensen, J.S.,Khelashvili, G.,Quick, M.,Terry, D.S.,Missel, J.W.,LeVine, M.V.,Gourdon, P.,Blanchard, S.C.,Javitch, J.A.,Weinstein, H.,Loland, C.J.,Nissen, P.,Gether, U.
X-ray structure of LeuT in an inward-facing occluded conformation reveals mechanism of substrate release.
Nat Commun, 11:1005-1005, 2020

PubMed Abstract: Neurotransmitter:sodium symporters (NSS) are conserved from bacteria to man and serve as targets for drugs, including antidepressants and psychostimulants. Here we report the X-ray structure of the prokaryotic NSS member, LeuT, in a Na/substrate-bound, inward-facing occluded conformation. To obtain this structure, we were guided by findings from single-molecule fluorescence spectroscopy and molecular dynamics simulations indicating that L-Phe binding and mutation of the conserved N-terminal Trp8 to Ala both promote an inward-facing state. Compared to the outward-facing occluded conformation, our structure reveals a major tilting of the cytoplasmic end of transmembrane segment (TM) 5, which, together with release of the N-terminus but without coupled movement of TM1, opens a wide cavity towards the second Na binding site. The structure of this key intermediate in the LeuT transport cycle, in the context of other NSS structures, leads to the proposal of an intracellular release mechanism of substrate and ions in NSS proteins.

PubMed: 32081981
DOI: 10.1038/s41467-020-14735-w

Experimental method

X-RAY DIFFRACTION (2.6 Å)