Interaction of GAPR-1 with lipid bilayers is regulated by alternative homodimerization
van Galen, Josse; Olrichs, Nick K; Schouten, Arie; Serrano, Ramon L; Nolte-'t Hoen, Esther N M; Eerland, Ruud; Kaloyanova, Dora; Gros, Piet; Helms, J Bernd
(2012) Biochimica et Biophysica Acta, volume 1818, issue 9, pp. 2175 - 2183
(Article)
Abstract
Golgi-Associated Plant Pathogenesis-Related protein 1 (GAPR-1) is a mammalian protein that belongs to the superfamily of plant pathogenesis related proteins group 1 (PR-1). GAPR-1 is a peripheral membrane-binding protein that strongly associates with lipid-enriched microdomains at the cytosolic leaflet of Golgi membranes. Little is known about the mechanism of GAPR-1
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interaction with membranes. We previously suggested that dimerization plays a role in the function of GAPR-1 and here we report that phytic acid (inositol hexakisphosphate) induces dimerization of GAPR-1 in solution. Elucidation of the crystal structure of GAPR-1 in the presence of phytic acid revealed that the GAPR-1 dimer differs from the previously published GAPR-1 dimer structure. In this structure, one of the monomeric subunits of the crystallographic dimer is rotated by 28.5°. To study the GAPR-1 dimerization properties, we investigated the interaction with liposomes in a light scattering assay and by flow cytometry. In the presence of negatively charged lipids, GAPR-1 caused a rapid and stable tethering of liposomes. [D81K]GAPR-1, a mutant predicted to stabilize the IP6-induced dimer conformation, also caused tethering of liposomes. [A68K]GAPR-1 however, a mutant predicted to stabilize the non-rotated dimer conformation, is capable of binding to liposomes but did not cause liposome tethering. Our combined data suggest that the charge properties of the lipid bilayer can regulate GAPR-1 dynamics as a potential mechanism to modulate GAPR-1 function.
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Keywords: Cell Membrane, Chromatography, Gel, Crystallography, X-Ray, Dimerization, Flow Cytometry, Golgi Apparatus, Humans, Lipid Bilayers, Lipids, Liposomes, Membrane Proteins, Models, Biological, Models, Molecular, Molecular Conformation, Mutation, Phosphatidylinositols, Phytic Acid, Plasmids, Protein Conformation, Ordered by external client
ISSN: 0006-3002
Note: Copyright © 2012 Elsevier B.V. All rights reserved.
(Peer reviewed)