Integration of two RAB5 groups during endosomal transport in plants (OA) (eLIFE)

RAB proteins are membrane-anchored proteins that coordinate and regulate vesicle trafficking. Plants contain two group of RAB5 proteins, canonical (ARA7, RHA1) and plant-specific (ARA6), which share a common activator, VPS9A (Vacuolar Protein Sorting 9A). Ito et al. used an activated (GTP-bound) version of the plant-specific ARA6 to find interacting partner proteins. From that screening, they identified PUF2 (PLANT UNIQUE RAB5 EFFECTOR 2) as an effector molecule of ARA6. Surprisingly, PUF2 also interacts with inactivated (GDP-bound) canonical RAB5 and the common RAB5 effector (VPS9A). Based on biochemical and genetic evidence, the authors found that PUF2 recruits VPS9A as well as inactive canonical RAB5 to the endosomal membrane and facilitates its activation. However, ARA6 negatively regulates the PUF2-mediated RAB5 activation. This mechanistic model explained the pivotal role of PUF2 to regulate and integrate two groups of RAB5 in plant. (Summary by Arif Ashraf) eLife: 10.7554/eLife.34064.001