The vacuole of the yeast Saccharomyces cerevisiae functions comparably to the mammalian lysosome. Its functions include protein degradation, pH/ion homeostasis, down regulation of cell surface receptors, and the ability to adapt to different environmental stresses. Defects in lysosomal trafficking are implicated with neurodegenerative diseases; therefore, understanding vacuolar trafficking will lead to more insight into lysosomal trafficking. Through our genome wide screen to identify mutants defective in the late stages of vacuolar trafficking, our lab has uncovered several previously uncharacterized ENdosome and Vacuole interface (ENV) genes. This study is focused on the characterization of ENV7, a putative serine/threonine kinase that has 29% identity to the human STK16 kinase whose function is unknown. Complementation experiments show that ENV7 is responsible for correct processing of Carboxypeptidase Y. Overexpression of the gene results in no pleiotropic phenotypes within the parameters tested. Env7p localizes at the vacuolar membrane which led to further examination of the deletion mutant, env7Δ, in vacuolar events. Microscopic analyses of env7Δ reveal no vacuolar morphology, bulk endocytic trafficking, and acidification function defects comparable to WT (BY4742). Growth assays reveal no fitness survival, and pH/ion homeostasis defects associated with env7Δ. Overall, this study establishes that ENV7 is localized to the vacuolar membrane and is involved in vacuolar protein processing independent of vacuolar morphology and acidification functions.
|Commitee:||Khatra, Balwant, Lee-Fruman, Kay|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 51/04M(E), Masters Abstracts International|
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