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J Biol Chem
2012 May 18;28721:17198-17205. doi: 10.1074/jbc.M112.355040.
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Conserved asparagine residue located in binding pocket controls cation selectivity and substrate interactions in neuronal glutamate transporter.
Teichman S
,
Qu S
,
Kanner BI
.
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Transporters of the major excitatory neurotransmitter glutamate play a crucial role in glutamatergic neurotransmission by removing their substrate from the synaptic cleft. The transport mechanism involves co-transport of glutamic acid with three Na(+) ions followed by countertransport of one K(+) ion. Structural work on the archeal homologue Glt(Ph) indicates a role of a conserved asparagine in substrate binding. According to a recent proposal, this residue may also participate in a novel Na(+) binding site. In this study, we characterize mutants of this residue from the neuronal transporter EAAC1, Asn-451. None of the mutants, except for N451S, were able to exhibit transport. However, the K(m) of this mutant for l-aspartate was increased ∼30-fold. Remarkably, the increase for d-aspartate and l-glutamate was 250- and 400-fold, respectively. Moreover, the cation specificity of N451S was altered because sodium but not lithium could support transport. A similar change in cation specificity was observed with a mutant of a conserved threonine residue, T370S, also implicated to participate in the novel Na(+) site together with the bound substrate. In further contrast to the wild type transporter, only l-aspartate was able to activate the uncoupled anion conductance by N451S, but with an almost 1000-fold reduction in apparent affinity. Our results not only provide experimental support for the Na(+) site but also suggest a distinct orientation of the substrate in the binding pocket during the activation of the anion conductance.
Arriza,
Excitatory amino acid transporter 5, a retinal glutamate transporter coupled to a chloride conductance.
1997, Pubmed,
Xenbase
Arriza,
Excitatory amino acid transporter 5, a retinal glutamate transporter coupled to a chloride conductance.
1997,
Pubmed
,
Xenbase
Bendahan,
Arginine 447 plays a pivotal role in substrate interactions in a neuronal glutamate transporter.
2000,
Pubmed
,
Xenbase
Bergles,
Comparison of coupled and uncoupled currents during glutamate uptake by GLT-1 transporters.
2002,
Pubmed
Borre,
Coupled, but not uncoupled, fluxes in a neuronal glutamate transporter can be activated by lithium ions.
2001,
Pubmed
Borre,
Arginine 445 controls the coupling between glutamate and cations in the neuronal transporter EAAC-1.
2004,
Pubmed
Boudker,
Coupling substrate and ion binding to extracellular gate of a sodium-dependent aspartate transporter.
2007,
Pubmed
Brew,
Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells.
,
Pubmed
Crisman,
Inward-facing conformation of glutamate transporters as revealed by their inverted-topology structural repeats.
2009,
Pubmed
,
Xenbase
Fairman,
An excitatory amino-acid transporter with properties of a ligand-gated chloride channel.
1995,
Pubmed
,
Xenbase
Grewer,
Glutamate translocation of the neuronal glutamate transporter EAAC1 occurs within milliseconds.
2000,
Pubmed
Grewer,
Individual subunits of the glutamate transporter EAAC1 homotrimer function independently of each other.
2005,
Pubmed
Groeneveld,
Na(+):aspartate coupling stoichiometry in the glutamate transporter homologue Glt(Ph).
2010,
Pubmed
Groeneveld,
Rigidity of the subunit interfaces of the trimeric glutamate transporter GltT during translocation.
2007,
Pubmed
Grunewald,
The accessibility of a novel reentrant loop of the glutamate transporter GLT-1 is restricted by its substrate.
2000,
Pubmed
Grunewald,
Biotinylation of single cysteine mutants of the glutamate transporter GLT-1 from rat brain reveals its unusual topology.
1998,
Pubmed
Holmseth,
Specificity of antibodies: unexpected cross-reactivity of antibodies directed against the excitatory amino acid transporter 3 (EAAT3).
2005,
Pubmed
Kanai,
Primary structure and functional characterization of a high-affinity glutamate transporter.
1992,
Pubmed
,
Xenbase
Kanner,
Active transport of L-glutamate by membrane vesicles isolated from rat brain.
1978,
Pubmed
Kanner,
Binding order of substrates to the sodium and potassium ion coupled L-glutamic acid transporter from rat brain.
1982,
Pubmed
Kavanaugh,
Mutation of an amino acid residue influencing potassium coupling in the glutamate transporter GLT-1 induces obligate exchange.
1997,
Pubmed
Koch,
Small-scale molecular motions accomplish glutamate uptake in human glutamate transporters.
2005,
Pubmed
,
Xenbase
Koch,
The glutamate-activated anion conductance in excitatory amino acid transporters is gated independently by the individual subunits.
2007,
Pubmed
,
Xenbase
Kunkel,
Rapid and efficient site-specific mutagenesis without phenotypic selection.
1987,
Pubmed
Larsson,
Evidence for a third sodium-binding site in glutamate transporters suggests an ion/substrate coupling model.
2010,
Pubmed
,
Xenbase
Leary,
The glutamate and chloride permeation pathways are colocalized in individual neuronal glutamate transporter subunits.
2007,
Pubmed
,
Xenbase
Levy,
Stoichiometry of the glial glutamate transporter GLT-1 expressed inducibly in a Chinese hamster ovary cell line selected for low endogenous Na+-dependent glutamate uptake.
1998,
Pubmed
Menaker,
The substrate specificity of a neuronal glutamate transporter is determined by the nature of the coupling ion.
2006,
Pubmed
Nelson,
Hydrogen ion cotransport by the renal brush border glutamate transporter.
1983,
Pubmed
Otis,
Isolation of current components and partial reaction cycles in the glial glutamate transporter EAAT2.
2000,
Pubmed
Pines,
Counterflow of L-glutamate in plasma membrane vesicles and reconstituted preparations from rat brain.
1990,
Pubmed
Pines,
Glutamate 404 is involved in the substrate discrimination of GLT-1, a (Na+ + K+)-coupled glutamate transporter from rat brain.
1995,
Pubmed
Reyes,
Transport mechanism of a bacterial homologue of glutamate transporters.
2009,
Pubmed
Rosental,
A conserved methionine residue controls the substrate selectivity of a neuronal glutamate transporter.
2010,
Pubmed
,
Xenbase
Rosental,
Multiple consequences of mutating two conserved beta-bridge forming residues in the translocation cycle of a neuronal glutamate transporter.
2006,
Pubmed
Slotboom,
A conserved serine-rich stretch in the glutamate transporter family forms a substrate-sensitive reentrant loop.
1999,
Pubmed
Tao,
Mechanism of cation binding to the glutamate transporter EAAC1 probed with mutation of the conserved amino acid residue Thr101.
2010,
Pubmed
Teichman,
The equivalent of a thallium binding residue from an archeal homolog controls cation interactions in brain glutamate transporters.
2009,
Pubmed
,
Xenbase
Teichman,
Aspartate-444 is essential for productive substrate interactions in a neuronal glutamate transporter.
2007,
Pubmed
,
Xenbase
Wadiche,
Macroscopic and microscopic properties of a cloned glutamate transporter/chloride channel.
1998,
Pubmed
,
Xenbase
Wadiche,
Ion fluxes associated with excitatory amino acid transport.
1995,
Pubmed
,
Xenbase
Wadiche,
Kinetics of a human glutamate transporter.
1995,
Pubmed
,
Xenbase
Watzke,
Early intermediates in the transport cycle of the neuronal excitatory amino acid carrier EAAC1.
2001,
Pubmed
Yamashita,
Crystal structure of a bacterial homologue of Na+/Cl--dependent neurotransmitter transporters.
2005,
Pubmed
Yernool,
Structure of a glutamate transporter homologue from Pyrococcus horikoshii.
2004,
Pubmed
Zerangue,
Flux coupling in a neuronal glutamate transporter.
1996,
Pubmed
,
Xenbase
Zhang,
Two serine residues of the glutamate transporter GLT-1 are crucial for coupling the fluxes of sodium and the neurotransmitter.
1999,
Pubmed
Zhang,
Molecular determinant of ion selectivity of a (Na+ + K+)-coupled rat brain glutamate transporter.
1998,
Pubmed
