The dynamin-related protein Vps1 regulates vacuole fission, fusion and tubulation in the fission yeast, Schizosaccharomyces pombe

Fission yeast cells lacking the dynamin-related protein (DAP) Vps1 had smaller vacuoles with reduced capacity for both fusion and fission in response to hypotonic and hypertonic conditions respectively. vps1 Delta cells showed normal vacuolar protein sorting, actin organisation and endocytosis. Over-expression of vps1 transformed vacuoles from spherical to tubular. Tubule formation was enhanced in fission conditions and required the Rab protein Ypt7. Vacuole tubulation by Vps1 was more extensive in the absence of a second DRP, Dnm1. Both dnm1 Delta and the double mutant vps1 Delta dnm1 Delta showed vacuole fission defects similar to that of vps1 Delta. Over-expression of vps1 in dnm1 Delta, or of dnm1 in vps1 Delta failed to rescue this phenotype. Over-expression of dnm1 in wild-type cells, on the other hand, induced vacuole fission. Our results are consistent with a model of vacuole fission in which Vps1 creates a tubule of an appropriate diameter for subsequent scission by Dnm1. (C) 2009 Elsevier Inc. All rights reserved.