Rab7- and HOPS-dependent membrane fusion at the plant vacuole

Cargo bound for the plant lytic vacuole, from prevacuolar compartments, the biosynthetic route and autophagy, arrives by membrane fusion with the tonoplast. The Mon1-Ccz1 complex activates the Rab7 GTPase (RabG3 in plants) on the incoming membrane, Rab7 recruits the HOPS tethering complex, and HOPS assembles the vacuolar SNAREs, the Qa-SNARE SYP22 with VTI11 and their partners, which fuse the two bilayers. This module is the green-lineage form of that step, written so that it can be evaluated in a plant genome.

Viridiplantae scope, with Arabidopsis representatives. The machinery is conserved across eukaryotes and several selectors (Vps41, Ccz1) are eukaryote-wide subfamilies, but the Rab7 and SNARE selectors list plant members only, so the module is written for plants. Read as a satisfiability rule, a genome needs Mon1 and Ccz1, a RabG3 GTPase, the Vps41 and Vps39 HOPS subunits, and the SYP22 and VTI11 SNAREs. Every step is required. Named lineage exception: the RabG3 step misses chlorophyte Rab7 and some angiosperm Rab7 entries (cotton), which PANTHER places in the pan-eukaryotic subfamily PTHR47981:SF20 (see that step), so the rule is grounded for the angiosperm RabG3B-F subfamilies rather than across Viridiplantae. Partial rule: the HOPS core subunits VPS11, VPS16, VPS18 and VPS33, the Qc-SNARE SYP51 and the R-SNARE VAMP713 are not modelled, and nor is the Rab7-independent, AP-3-mediated route from the Golgi. Steps whose PAINT nodes carry no F IBD (RabG3, Vps41, Vps39) are left untyped. Fungal and animal selectors for the Rab7 and SNARE steps, and SF49 rather than SF27 for Vps39 (see that step), would extend the module to the yeast vacuole and the lysosome.