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)

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 S1P₁ 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, S1P₄. This mutation severely affected the response of S1P₄ to S1P in a [³⁵S]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 S1P₄ 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 S1P₁ 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 > School of Molecular Biosciences
• 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.