Mid2 is a putative sensor for cell integrity signaling in Saccharomyces cerevisiae

Area of Science:

• Cell Biology
• Molecular Biology
• Yeast Genetics

Background:

• Hcs77 is a putative cell surface sensor crucial for cell integrity signaling in Saccharomyces cerevisiae.
• Loss of Hcs77 function leads to cell lysis at elevated temperatures and impaired heat shock signaling.
• The Mpk1 mitogen-activated protein kinase pathway is involved in cell integrity signaling.

Purpose of the Study:

• To identify genes that suppress the cell lysis defect of hcs77 null mutants.
• To elucidate the roles of Mid2 and Hcs77 in cell integrity signaling.
• To investigate the function of a novel MID2 homolog, MTL1.

Main Methods:

• Gene cloning and dosage suppression screening.
• Analysis of cell lysis and survival under various stress conditions (heat shock, pheromone treatment).
• Protein localization and modification analysis (O-mannosylation).

Main Results:

• MID2 was identified as a dosage suppressor of hcs77 null mutant cell lysis.
• Mid2 is a membrane protein essential for survival of pheromone treatment and cell integrity signaling.
• Hcs77 and Mid2 function redundantly as cell surface sensors for cell integrity during vegetative growth.
• MTL1, a MID2 homolog, provides partial redundancy for cell integrity signaling at elevated temperatures.

Conclusions:

• Hcs77 and Mid2 are essential, redundant cell surface sensors for cell integrity signaling in yeast.
• Mid2 has a primary role in signaling during pheromone-induced morphogenesis, while Hcs77 is dedicated to vegetative growth.
• MTL1 partially complements Mid2 function under specific stress conditions.