HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 31, 21519-21529, August 1, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/31/21519    most recent M709190200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Blanke, M. L. Articles by VanDongen, A. M. J. PubMed PubMed Citation Articles by Blanke, M. L. Articles by VanDongen, A. M. J. Social Bookmarking                      What's this?

Constitutive Activation of the N-Methyl-D-aspartate Receptor via Cleft-spanning Disulfide Bonds^*

From the Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, 27710

Although the N-methyl-D-aspartate (NMDA) receptor plays a critical role in the central nervous system, many questions remain regarding the relationship between its structure and functional properties. In particular, the involvement of ligand-binding domain closure in determining agonist efficacy, which has been reported in other glutamate receptor subtypes, remains unresolved. To address this question, we designed dual cysteine point mutations spanning the NR1 and NR2 ligand-binding clefts, aiming to stabilize these domains in closed cleft conformations. Two mutants, E522C/I691C in NR1 (EI) and K487C/N687C in NR2 (KN) were found to exhibit significant glycine- and glutamate-independent activation, respectively, and co-expression of the two subunits produced a constitutively active channel. However, both individual mutants could be activated above constitutive levels in a concentration-dependent manner, indicating that cleft closure does not completely prevent agonist association. Interestingly, whereas the NR2 KN disulfide was found to potentiate channel gating and M3 accessibility, NR1 EI exhibited the opposite phenotype, suggesting that the EI disulfide may trap the NR1 ligand-binding domain in a lower efficacy conformation. Furthermore, both mutants affected agonist sensitivity at the opposing subunit, suggesting that closed cleft stabilization may contribute to coupling between the subunits. These results support a correlation between cleft stability and receptor activation, providing compelling evidence for the Venus flytrap mechanism of glutamate receptor domain closure.

Received for publication, November 8, 2007 , and in revised form, April 30, 2008.

^* This work was supported, in whole or in part, by National Institutes of Health Grants F31 NS053030-01 (to M. L. B.) and R01-MH61506 (to A. M. J. V. D.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Program in Neuroscience, Duke-NUS Graduate Medical School, 2 Jalan Bukit Merah, Singapore 169547, Singapore. Tel.: (65) 6516–7075; Fax: (65) 6534–8632; E-mail: vando005{at}mc.duke.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?