Department of Anesthesiology

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Direct visualization of glutamate transporter elevator mechanism by high-speed AFM.

TitleDirect visualization of glutamate transporter elevator mechanism by high-speed AFM.
Publication TypeJournal Article
Year of Publication2017
AuthorsRuan Y, Miyagi A, Wang X, Chami M, Boudker O, Scheuring S
JournalProc Natl Acad Sci U S A
Volume114
Issue7
Pagination1584-1588
Date Published2017 Feb 14
ISSN1091-6490
Abstract

Glutamate transporters are essential for recovery of the neurotransmitter glutamate from the synaptic cleft. Crystal structures in the outward- and inward-facing conformations of a glutamate transporter homolog from archaebacterium Pyrococcus horikoshii, sodium/aspartate symporter GltPh, suggested the molecular basis of the transporter cycle. However, dynamic studies of the transport mechanism have been sparse and indirect. Here we present high-speed atomic force microscopy (HS-AFM) observations of membrane-reconstituted GltPh at work. HS-AFM movies provide unprecedented real-space and real-time visualization of the transport dynamics. Our results show transport mediated by large amplitude 1.85-nm "elevator" movements of the transport domains consistent with previous crystallographic and spectroscopic studies. Elevator dynamics occur in the absence and presence of sodium ions and aspartate, but stall in sodium alone, providing a direct visualization of the ion and substrate symport mechanism. We show unambiguously that individual protomers within the trimeric transporter function fully independently.

DOI10.1073/pnas.1616413114
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID28137870
PubMed Central IDPMC5320997
Grant ListR37 NS085318 / NS / NINDS NIH HHS / United States