Mechanisms Governing the Endosomal Membrane Recruitment of the Core Retromer in Arabidopsis

• Published in: The Journal of biological chemistry Vol. 288; no. 13; pp. 8815 - 8825
• Main Authors: Zelazny, Enric, Santambrogio, Martina, Pourcher, Mikael, Chambrier, Pierre, Berne-Dedieu, Annick, Fobis-Loisy, Isabelle, Miège, Christine, Jaillais, Yvon, Gaude, Thierry
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 29.03.2013; American Society for Biochemistry and Molecular Biology
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Cytosol - metabolism; Endosomes; Endosomes - metabolism; Genotype; Immunochemistry - methods; Intracellular Trafficking; Life Sciences; Microscopy, Confocal - methods; Mutagenesis, Site-Directed; Mutation; Phenotype; Plant Biology; Plant Physiological Phenomena; Plant Roots - metabolism; Plants, Genetically Modified - metabolism; Plasmids - metabolism; Protein Complexes; rab GTP-Binding Proteins - genetics; rab GTP-Binding Proteins - metabolism; RAB GTPases; Rab Proteins; Reproductive Biology; Retromer; Subcellular Fractions - metabolism; Two-Hybrid System Techniques; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - metabolism; VPS Proteins; Protein Complexes; Arabidopsis thaliana; RAB GTPases; VPS Proteins; Arabidopsis; Rab Proteins; Intracellular Trafficking; Retromer; Endosomes; retromer; vps proteins; endosomes; intracellular trafficking; rab gtpases; rab proteins; protein complexes; arabidopsis thaliana; arabidopsis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.440503

The retromer complex localizes to endosomal membranes and is involved in protein trafficking. In mammals, it is composed of a dimer of sorting nexins and of the core retromer consisting of vacuolar protein sorting (VPS)26, VPS29, and VPS35. Although homologs of these proteins have been identified in plants, how the plant retromer functions remains elusive. To better understand the role of VPS components in the assembly and function of the core retromer, we characterize here Arabidopsis vps26-null mutants. We show that impaired VPS26 function has a dramatic effect on VPS35 levels and causes severe phenotypic defects similar to those observed in vps29-null mutants. This implies that functions of plant VPS26, VPS29, and VPS35 are tightly linked. Then, by combining live-cell imaging with immunochemical and genetic approaches, we report that VPS35 alone is able to bind to endosomal membranes and plays an essential role in VPS26 and VPS29 membrane recruitment. We also show that the Arabidopsis Rab7 homolog RABG3f participates in the recruitment of the core retromer to the endosomal membrane by interacting with VPS35. Altogether our data provide original information on the molecular interactions that mediate assembly of the core retromer in plants. Background: The retromer is an endosome-localized complex involved in intracellular trafficking that remains understudied in plants. Results:Arabidopsis vacuolar protein sorting (VPS)35 plays a key role in the membrane recruitment of the retromer and interacts with a Rab7 homolog, RABG3f. Conclusion: We propose a model in which plant retromer membrane recruitment involves RABG3f/VPS35 interaction. Significance: The plant retromer exhibits original mechanistic features compared with other organisms.