RRC ID 47234
Author Wen L, Fukuda M, Sunada M, Ishino S, Ishino Y, Okita TW, Ogawa M, Ueda T, Kumamaru T.
Title Guanine nucleotide exchange factor 2 for Rab5 proteins coordinated with GLUP6/GEF regulates the intracellular transport of the proglutelin from the Golgi apparatus to the protein storage vacuole in rice endosperm.
Journal J Exp Bot
Abstract Rice glutelin polypeptides are initially synthesized on the endoplasmic reticulum (ER) membrane as a proglutelin, which are then transported to the protein storage vacuole (PSV) via the Golgi apparatus. Rab5 and its cognate activator guanine nucleotide exchange factor (GEF) are essential for the intracellular transport of proglutelin from the Golgi apparatus to the PSV. Results from previous studies showed that the double recessive type of glup4/rab5a and glup6/gef mutant accumulated much higher amounts of proglutelin than either parent line. The present study demonstrates that the double recessive type of glup4/rab5a and glup6/gef mutant showed not only elevated proglutelin levels and much larger paramural bodies but also reduced the number and size of PSVs, indicating a synergistic mutation effect. These observations led us to the hypothesis that other isoforms of Rab5 and GEF also participate in the intracellular transport of rice glutelin. A database search identified a novel guanine nucleotide exchange factor, Rab5-GEF2. Like GLUP6/GEF, Rab5-GEF2 was capable of activating Rab5a and two other Rab5 isoforms in in vitro GTP/GDP exchange assays. GEF proteins consist of the helical bundle (HB) domain at the N-terminus, Vps9 domain, and a C-terminal region. By the deletion analysis of GEFs, the HB domain was found essential for the activation of Rab5 proteins.
Volume 66(20)
Pages 6137-47
Published 2015-10-1
DOI 10.1093/jxb/erv325
PII erv325
PMID 26136263
PMC PMC4588877
MeSH Endosperm Glutens / metabolism* Golgi Apparatus / metabolism Guanine Nucleotide Exchange Factors / genetics Guanine Nucleotide Exchange Factors / metabolism Molecular Sequence Data Mutation Oryza / genetics* Oryza / metabolism Plant Proteins / genetics* Plant Proteins / metabolism Protein Transport / genetics Sequence Analysis, DNA Vacuoles / metabolism rab5 GTP-Binding Proteins / genetics rab5 GTP-Binding Proteins / metabolism
IF 5.908
Times Cited 9
Rice Induced mutation lines