# Spindle checkpoint activation by fungal orthologs of the S. cerevisiae Mps1 kinase

## TL;DR

Researchers explored using Mps1 kinase from pathogenic fungi in a budding yeast system to develop new antifungal drugs.

## Contribution

The study adapts a budding yeast system to express Mps1 orthologs from pathogenic fungi for antifungal drug screening.

## Key findings

- Overexpression of Mps1 orthologs from pathogenic fungi caused cell cycle arrest in budding yeast.
- Two fungal Mps1 orthologs produced phenotypes similar to budding yeast Mps1, validating the assay system.
- The system shows potential for identifying inhibitors of Mps1 enzymatic activity as antifungal agents.

## Abstract

There is an ongoing need for antifungal agents to treat humans. Identification of new antifungal agents can be based on screening compounds using whole cell assays. Screening compounds that target a particular molecule is possible in budding yeast wherein sophisticated strain engineering allows for controlled expression of endogenous or heterologous genes. We have considered the yeast Mps1 protein kinase as a reasonable target for antifungal agents because mutant or druggable forms of the protein, upon inactivation, cause rapid loss of cell viability. Furthermore, extensive analysis of the Mps1 in budding yeast has offered potential tactics for identifying inhibitors of its enzymatic activity. One such tactic is based on the finding that overexpression of Mps1 leads to cell cycle arrest via activation of the spindle assembly checkpoint. We have endeavored to adapt this assay to be based on the overexpression of Mps1 orthologs from pathogenic yeast in hopes of having a whole-cell assay system to test the activity of these orthologs. Mps1 orthologous genes from seven pathogenic yeast or other pathogenic fungal species were isolated and expressed in budding yeast. Two orthologs clearly produced phenotypes similar to those produced by the overexpression of budding yeast Mps1, indicating that this system for heterologous Mps1 expression has potential as a platform for identifying prospective antifungal agents.