The GRV2/RME-8 Protein of Arabidopsis Functions in the Late Endocytic Pathway and Is Required for Vacuolar Membrane Flow

Plant J. 2008 Jan;53(1):29-41. doi: 10.1111/j.1365-313X.2007.03314.x. Epub 2007 Oct 27.

Abstract

The gravitropism defective 2 (grv2) mutants of Arabidopsis thaliana were previously characterized as exhibiting shoot agravitropism resulting from mutations in a homolog of the Caenorhabditis elegans RECEPTOR-MEDIATED ENDOCYTOSIS-8 (RME-8) gene, which is required in C. elegans for endocytosis. A fluorescent protein fusion to the GRV2 protein localized to endosomes in transgenic plants, and vacuolar morphology was altered in grv2 mutants. A defect in vacuolar membrane dynamics provides a mechanistic explanation for the gravitropic defect, and may also account for the presence of an enlarged vacuole in early embryos, together with a nutrient requirement during seedling establishment. The GRV2-positive endosomes were sensitive to Wortmannin but not brefeldin A (BFA), consistent with GRV2 operating late in the endocytic pathway, prior to delivery of vesicles to the central vacuole. The specific enlargement of GRV2:YFP structures by Wortmannin, together with biochemical data showing that GRV2 co-fractionates with pre-vacuolar markers such as PEP12/SYP21, leads us to conclude that in plants GRV2/RME-8 functions in vesicle trafficking from the multivesicular body/pre-vacuolar compartment to the lytic vacuole.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Androstadienes / pharmacokinetics
  • Androstadienes / pharmacology
  • Animals
  • Arabidopsis / genetics*
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / metabolism*
  • Brefeldin A / pharmacology
  • Caenorhabditis elegans / physiology
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Endocytosis / physiology*
  • Endosomes / drug effects
  • Endosomes / metabolism
  • Endosomes / physiology*
  • Gravitropism / genetics
  • Gravitropism / physiology
  • Intracellular Membranes / metabolism
  • Mutation
  • Vacuoles / metabolism
  • Vacuoles / physiology
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*
  • Vesicular Transport Proteins / physiology
  • Wortmannin

Substances

  • Androstadienes
  • Arabidopsis Proteins
  • Drosophila Proteins
  • KAM2 protein, Arabidopsis
  • Rme-8 protein, Drosophila
  • Vesicular Transport Proteins
  • Brefeldin A
  • Wortmannin