Effect of GTP-binding protein (YPT1 protein) on the enhanced yeast vacuolar activity.

Yeast GTP-binding protein (YPT1 protein) has been reported to function in the early stages of the secretory pathway. Particularly, YPT1 protein is observed to regulate both the endoplasmic reticulum-to-Golgi transport and the autophagy. Therefore, the YPT1 protein overexpressed in yeast vacuoles is expected to enhance antimicrobial and anticancer activity. The enhancement of yeast vacuolar activity under the overexpression of YPT1 was evaluated by the analysis of lysozyme activity, antimicrobial activity against Escherichia coli and Staphylococcus aureus, and MTT assay against HeLa cell lines. Additionally, the rise in concentration of some important proteinases inside the vacuole, such as proteinase A, proteinase B, and vacuolar carboxypeptidase Y (CPY) were also recorded using a 2DE technique. All results imply YPT1 involvement in the recruitment of some specific proteinases into vacuoles, which leads to the enhancement of vacuolar activity. Since these there proteinases belong to the CPY pathway, YPT1 is even believed to up-regulate this trafficking pathway in yeast cells. Future studies, however, should be carried out to discover the mechanisms that allow YPT1 to recruit these proteins into yeast vacuoles.