S. cerevisiae ENV9, ENV10 and ENV11 Are Novel Genes Involved in Lysosomal Vacuole Events and their Products Localize to Lipid Droplets, ER, and Nucleus, Respectively

Abstract

ENV9, ENV10 and ENV11 are novel genes uncovered by a genome wide immunodetection screen for mutants defective in processing of the vacuolar enzyme carboxypeptidase Y at late endosome to vacuole interface. Additionally, env9Δ has minor growth sensitivity to caffeine and vesiculated vacuoles, while env10Δ and env11Δ are cold sensitive and the latter has increased fragmented vacuoles. Here, we report on the localization of their GFP and hemagglutinin (HA) tagged constructs as assessed by confocal microscopy and biochemical subcellular fractionation. Env9p localizes to lipid droplets and its possible role in lipid droplet morphology is under investigation. Env10p localizes to the ER and putative negative genetic interactions between ENV9 and ENV10 are under investigation. Env11p localizes to the nucleus and bioinformatic analyses identify a putative BED zinc finger DNA binding domain. Recently, Env11p and Vid22p, another gene product involved in vacuolar protein trafficking, have been reported to colocalize with the transcription factor Tbf1 at selected promoter regions. These findings suggest that Env9p and Env10p play a direct role within the endomembrane flux in vacuolar protein trafficking while Env11p may be indirectly related through transcriptional regulation of vacuolar related genes. NIH‐AREA grant GM085794, CSULB Leonard Scholarship (LR) and an NSF‐MRI grant for the confocal microscope.