The RAVE complex is essential for stable assembly of the yeast V-ATPase

Vacuolar proton-translocating ATPases are composed of a peripheral complex, V-1, attached to an integral membrane complex, V.. Association of the two complexes is essential for ATP-driven proton transport and is regulated post-translationally in response to glucose concentration. A new complex, RAVE, was recently isolated and implicated in glucose-dependent reassembly of V-ATPase complexes that had disassembled in response to glucose deprivation (Seol, J. H., Shevchenko, A., and Deshaies, R. J. (2001) Nat. Cell Biol. 3, 384-391). Here, we provide evidence supporting a role for RAVE in reassembly of the V-ATPase but also demonstrate an essential role in V-ATPase assembly under other conditions. The RAVE complex associates reversibly with V-1 complexes released from the membrane by glucose deprivation but binds constitutively to cytosolic V-1 sectors in a mutant lacking V-0 sectors. V-ATPase complexes from cells lacking RAVE subunits show serious structural and functional defects even in glucose-grown cells or in combination with a mutation that blocks disassembly of the V-ATPase. RAVE.V-1 interactions are specifically disrupted in cells lacking V-1 subunits E or G, suggesting a direct involvement for these subunits in interaction of the two complexes. Skp1p, a RAVE subunit involved in many different signal transduction pathways, binds stably to other RAVE subunits under conditions that alter RAVE.V-1 binding; thus, Skp1p recruitment to the RAVE complex does not appear to provide a signal for V-ATPase assembly.