TY - JOUR
T1 - X-ray structure of LeuT in an inward-facing occluded conformation reveals mechanism of substrate release
AU - Gotfryd, Kamil
AU - Boesen, Thomas
AU - Mortensen, Jonas S.
AU - Khelashvili, George
AU - Quick, Matthias
AU - Terry, Daniel S.
AU - Missel, Julie W.
AU - LeVine, Michael V.
AU - Gourdon, Pontus
AU - Blanchard, Scott C.
AU - Javitch, Jonathan A.
AU - Weinstein, Harel
AU - Loland, Claus J.
AU - Nissen, Poul
AU - Gether, Ulrik
PY - 2020/2/21
Y1 - 2020/2/21
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85079774084&partnerID=8YFLogxK
U2 - 10.1038/s41467-020-14735-w
DO - 10.1038/s41467-020-14735-w
M3 - Journal article
C2 - 32081981
AN - SCOPUS:85079774084
SN - 2041-1723
VL - 11
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 1005
ER -