Distinct sets of tethering complexes, SNARE complexes, and Rab GTPases mediate membrane fusion at the vacuole in Arabidopsis (PNAS)

In plant cells, vacuoles store and degrade wastes including proteins. Vacuolar targeting and fusion by endosomes are specified by SNARE complexes at the membrane. In this study, Takemoto et al. studied the function of two tethering complexes, HOPS (Homotypic fusion and Protein Sorting) and CORVET (Class C core vacuole/endosome tethering), that had previously not been studied in plants. The authors showed that HOPS and CORVET mediate distinct membrane fusion events at the vacuole, and that their roles in plants are distinct from their roles in yeast and animal cells. HOPS acts with the VAMP713-containing SNARE complex and RAB7 to mediate membrane fusion between vacuoles, while CORVET mediates membrane fusion between multivesicular endosomes and the vacuole, in coordination with RAB5 and the VAMP727-containing SNARE complex. This work “provides further evidence for the unique evolutionary diversification of the vacuolar transport system in plants.” (Summary by Arif Ashraf) PNAS: 10.1073/pnas.1717839115