A Conserved Leucine Occupies the Empty Substrate Site of LeuT in the Na+-free Return State

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A Conserved Leucine Occupies the Empty Substrate Site of LeuT in the Na+-free Return State. / Malinauskaite, Lina; Said, Saida; Sahin, Caglanur; Grouleff, Julie; Shahsavar, Azadeh; Bjerregaard, Henriette; Noer, Pernille Rimmer; Severinsen, Kasper; Boesen, Thomas; Schiøtt, Birgit; Sinning, Steffen; Nissen, Poul.

In: Nature Communications, Vol. 7, 11673, 2016.

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Malinauskaite, Lina ; Said, Saida ; Sahin, Caglanur ; Grouleff, Julie ; Shahsavar, Azadeh ; Bjerregaard, Henriette ; Noer, Pernille Rimmer ; Severinsen, Kasper ; Boesen, Thomas ; Schiøtt, Birgit ; Sinning, Steffen ; Nissen, Poul. / A Conserved Leucine Occupies the Empty Substrate Site of LeuT in the Na+-free Return State. In: Nature Communications. 2016 ; Vol. 7.

Bibtex

@article{b801e84943fb4b9ab6cf04c0ccc80718,
title = "A Conserved Leucine Occupies the Empty Substrate Site of LeuT in the Na+-free Return State",
abstract = "Bacterial members of the neurotransmitter:sodium symporter (NSS) family perform Na+-dependent amino-acid uptake and extrude H+ in return. Previous NSS structures represent intermediates of Na+/substrate binding or intracellular release, but not the inward-to-outward return transition. Here we report crystal structures of Aquifex aeolicus LeuT in an outward-oriented, Na+- and substrate-free state likely to be H+-occluded. We find a remarkable rotation of the conserved Leu25 into the empty substrate-binding pocket and rearrangements of the empty Na+ sites. Mutational studies of the equivalent Leu99 in the human serotonin transporter show a critical role of this residue on the transport rate. Molecular dynamics simulations show that extracellular Na+ is blocked unless Leu25 is rotated out of the substrate-binding pocket. We propose that Leu25 facilitates the inward-to-outward transition by compensating a Na+- and substrate-free state and acts as the gatekeeper for Na+ binding that prevents leak in inward-outward return transitions.",
author = "Lina Malinauskaite and Saida Said and Caglanur Sahin and Julie Grouleff and Azadeh Shahsavar and Henriette Bjerregaard and Noer, {Pernille Rimmer} and Kasper Severinsen and Thomas Boesen and Birgit Schi{\o}tt and Steffen Sinning and Poul Nissen",
year = "2016",
doi = "10.1038/ncomms11673",
language = "English",
volume = "7",
journal = "Nature Communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",

}

RIS

TY - JOUR

T1 - A Conserved Leucine Occupies the Empty Substrate Site of LeuT in the Na+-free Return State

AU - Malinauskaite, Lina

AU - Said, Saida

AU - Sahin, Caglanur

AU - Grouleff, Julie

AU - Shahsavar, Azadeh

AU - Bjerregaard, Henriette

AU - Noer, Pernille Rimmer

AU - Severinsen, Kasper

AU - Boesen, Thomas

AU - Schiøtt, Birgit

AU - Sinning, Steffen

AU - Nissen, Poul

PY - 2016

Y1 - 2016

N2 - Bacterial members of the neurotransmitter:sodium symporter (NSS) family perform Na+-dependent amino-acid uptake and extrude H+ in return. Previous NSS structures represent intermediates of Na+/substrate binding or intracellular release, but not the inward-to-outward return transition. Here we report crystal structures of Aquifex aeolicus LeuT in an outward-oriented, Na+- and substrate-free state likely to be H+-occluded. We find a remarkable rotation of the conserved Leu25 into the empty substrate-binding pocket and rearrangements of the empty Na+ sites. Mutational studies of the equivalent Leu99 in the human serotonin transporter show a critical role of this residue on the transport rate. Molecular dynamics simulations show that extracellular Na+ is blocked unless Leu25 is rotated out of the substrate-binding pocket. We propose that Leu25 facilitates the inward-to-outward transition by compensating a Na+- and substrate-free state and acts as the gatekeeper for Na+ binding that prevents leak in inward-outward return transitions.

AB - Bacterial members of the neurotransmitter:sodium symporter (NSS) family perform Na+-dependent amino-acid uptake and extrude H+ in return. Previous NSS structures represent intermediates of Na+/substrate binding or intracellular release, but not the inward-to-outward return transition. Here we report crystal structures of Aquifex aeolicus LeuT in an outward-oriented, Na+- and substrate-free state likely to be H+-occluded. We find a remarkable rotation of the conserved Leu25 into the empty substrate-binding pocket and rearrangements of the empty Na+ sites. Mutational studies of the equivalent Leu99 in the human serotonin transporter show a critical role of this residue on the transport rate. Molecular dynamics simulations show that extracellular Na+ is blocked unless Leu25 is rotated out of the substrate-binding pocket. We propose that Leu25 facilitates the inward-to-outward transition by compensating a Na+- and substrate-free state and acts as the gatekeeper for Na+ binding that prevents leak in inward-outward return transitions.

U2 - 10.1038/ncomms11673

DO - 10.1038/ncomms11673

M3 - Journal article

C2 - 27221344

VL - 7

JO - Nature Communications

JF - Nature Communications

SN - 2041-1723

M1 - 11673

ER -