Vac8: A Vacuolar Membrane Protein Required for Vacuole Inheritance and Nucleus-Vacuole Junction Formation

Abstract

Saccharomyces cerevisiae Vac8 is a vacuolar membrane protein, which functions in vacuole inheritance and fusion, nucleus-vacuole junctions, autophagy and the cytoplasm-to-vacuole-targeting pathway. Here, we analyzed Vac8 of the yeast Hansenula polymorpha . We show that Hp Vac8 localizes to the vacuolar membrane and concentrates in patches at nucleus-vacuole junctions. Analysis of a VAC8 deletion strain indicated that Hp Vac8 is required for vacuole inheritance and the formation of nuclear-vacuole junctions, but not for vacuole fusion. Previously, organelle proteomics resulted in the identification of Vac8 in peroxisomal fractions isolated from H. polymorpha and S. cerevisiae . However, deletion of H. polymorpha VAC8 had no effect on peroxisome biogenesis or peroxisome-vacuole contact sites.