A single amino acid determines preference between phospholipids and reveals length restriction for activation ofthe S1P4 receptor

Holdsworth, G., Osborne, D.A., Thi Pham, T., Fells, J.I., Hutchinson, G., Milligan, G. and Parrill, A.L. (2004) A single amino acid determines preference between phospholipids and reveals length restriction for activation ofthe S1P4 receptor. BMC Biochemistry, 5(12), (doi: 10.1186/1471-2091-5-12)

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Publisher's URL: http://dx.doi.org/10.1186/1471-2091-5-12

Abstract

Background<br/><br/> Sphingosine-1-phosphate and lysophosphatidic acid (LPA) are ligands for two related families of G protein-coupled receptors, the S1P and LPA receptors, respectively. The lysophospholipid ligands of these receptors are structurally similar, however recognition of these lipids by these receptors is highly selective. A single residue present within the third transmembrane domain (TM) of S1P receptors is thought to determine ligand selectivity; replacement of the naturally occurring glutamic acid with glutamine (present at this position in the LPA receptors) has previously been shown to be sufficient to change the specificity of S1P<sub>1</sub> from S1P to 18:1 LPA.<br/><br/> Results<br/><br/> We tested whether mutation of this "ligand selectivity" residue to glutamine could confer LPA-responsiveness to the related S1P receptor, S1P<sub>4</sub>. This mutation severely affected the response of S1P<sub>4</sub> to S1P in a [<sup>35</sup>S]GTPγS binding assay, and imparted sensitivity to LPA species in the order 14:0 LPA > 16:0 LPA > 18:1 LPA. These results indicate a length restriction for activation of this receptor and demonstrate the utility of using LPA-responsive S1P receptor mutants to probe binding pocket length using readily available LPA species. Computational modelling of the interactions between these ligands and both wild type and mutant S1P<sub>4</sub> receptors showed excellent agreement with experimental data, therefore confirming the fundamental role of this residue in ligand recognition by S1P receptors.<br/><br/> Conclusions<br/><br/> Glutamic acid in the third transmembrane domain of the S1P receptors is a general selectivity switch regulating response to S1P over the closely related phospholipids, LPA. Mutation of this residue to glutamine confers LPA responsiveness with preference for short-chain species. The preference for short-chain LPA species indicates a length restriction different from the closely related S1P<sub>1</sub> receptor.

Item Type:Articles
Additional Information:This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Milligan, Professor Graeme
Authors: Holdsworth, G., Osborne, D.A., Thi Pham, T., Fells, J.I., Hutchinson, G., Milligan, G., and Parrill, A.L.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:BMC Biochemistry
Publisher:BioMed Central Ltd.
ISSN:1471-2091
Copyright Holders:Copyright © 2004 Holdsworth et al; licensee BioMed Central Ltd.
First Published:First published in BMC Biochemistry 5(12)
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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