A SNARE Complex Unique to Seed Plants Is Required for Protein Storage Vacuole Biogenesis and Seed Development of Arabidopsis thaliana

摘要

The SNARE complex is a key regulator of vesicular traffic, executing membrane fusion between transport vesicles ornorganelles and target membranes. A functional SNARE complex consists of four coiled-coil helical bundles, three of which arensupplied by Q-SNAREs and another from an R-SNARE. Arabidopsis thaliana VAMP727 is an R-SNARE, with homologs only innseed plants. We have found that VAMP727 colocalizes with SYP22/ VAM3, a Q-SNARE, on a subpopulation of prevacuolarncompartments/endosomes closely associated with the vacuolar membrane. Genetic and biochemical analyses, includingnexamination of a synergistic interaction of vamp727 and syp22 mutations, histological examination of protein localization, andncoimmunoprecipitation from Arabidopsis lysates indicate that VAMP727 forms a complex with SYP22, VTI11, and SYP51 andnthat this complex plays a crucial role in vacuolar transport, seed maturation, and vacuole biogenesis. We suggest that thenVAMP727 complex mediates the membrane fusion between the prevacuolar compartment and the vacuole and that thisnprocess has evolved as an essential step for seed development.