Yeast as a Heterologous Model System to Uncover Type III Effector Function

Area of Science:

• Microbiology and Molecular Biology
• Bacterial Pathogenesis and Host-Pathogen Interactions
• Eukaryotic Cell Biology and Genetics

Background:

• Type III effectors (T3Es) are bacterial virulence proteins injected into host cells to disrupt cellular functions and cause disease.
• The budding yeast Saccharomyces cerevisiae offers a simplified eukaryotic system for studying T3Es due to low genetic redundancy and absence of host immunity.
• Yeast's genetic tractability and suitability for high-throughput studies have made it a valuable tool for analyzing over 100 T3Es from diverse pathogens.

Purpose of the Study:

• To critically evaluate the use of Saccharomyces cerevisiae as a model system for functional characterization of bacterial Type III effectors.
• To review the advantages and limitations of yeast in T3E research, including the identification of common effector targets and affected cellular processes.
• To discuss methodologies for structure-function studies, pathway analysis, and the discovery of novel antibacterial compounds using yeast-based screens.

Main Methods:

• Expression of plant and animal pathogen T3Es in Saccharomyces cerevisiae to observe phenotypic alterations.
• Analysis of T3E-induced changes in yeast cytoskeleton, Rho GTPases, MAPK signaling, vesicle trafficking, membrane dynamics, and programmed cell death.
• Application of transcriptomics, proteomics, and genetic screening approaches (suppressor, gain-of-function, synthetic lethality) to determine T3E functions.

Main Results:

• Yeast effectively reveals conserved T3E functions by perturbing fundamental eukaryotic processes, with cytoskeleton and Rho GTPases being frequent targets.
• T3Es in yeast commonly impact MAPK signaling, vesicle trafficking, membrane structures, and programmed cell death, reflecting their roles in native hosts.
• Yeast facilitates structure-function studies and the identification of T3E targets and pathways, enabling the discovery of molecules that inhibit effector function.

Conclusions:

• Saccharomyces cerevisiae is a versatile and powerful model for dissecting bacterial Type III effector mechanisms, host interactions, and for antimicrobial drug discovery.
• Despite limitations, yeast provides unique advantages for studying conserved cellular processes targeted by T3Es, offering insights into virulence and potential therapeutic strategies.
• Future applications of yeast in T3E research hold promise for advancing our understanding of pathogen biology and developing novel anti-infective agents.