Single-cell fluidic force microscopy reveals stress-dependent molecular interactions in yeast mating

Area of Science:

• Cell Biology
• Biophysics
• Microbiology

Background:

• Sexual agglutinins mediate cell aggregation and fusion in Saccharomyces cerevisiae during mating.
• Complementary agglutinins on 'a' and 'α' mating types bind to facilitate haploid cell fusion.
• Pheromone induction is necessary for agglutinin expression and function.

Purpose of the Study:

• To investigate the binding strength of single specific bonds between a- and α-agglutinins.
• To elucidate the role of mechanical forces and specific molecular components in agglutinin interactions.
• To understand the mechanism of enhanced adhesion during prolonged cell-cell contact.

Main Methods:

• Utilized an innovative single-cell manipulation assay combining fluidic force microscopy and force spectroscopy.
• Measured the force of single specific bonds between complementary yeast agglutinins.
• Investigated the impact of mechanical tension and specific molecular residues (disulfide bonds, H273) on binding.

Main Results:

• Quantified the strength of single specific bonds between a- and α-agglutinins at approximately 100 pN.
• Demonstrated that mechanical tension significantly enhances agglutinin interaction strength.
• Highlighted the critical roles of disulfide bonds in a-agglutinin and histidine residue H273 in α-agglutinin.

Conclusions:

• Mechanical stress induces conformational changes in agglutinins, transitioning them from a weak-binding folded state to a strong-binding extended state.
• Prolonged cell contact increases adhesion, likely due to enhanced agglutinin expression.
• The developed single-cell technology offers a promising approach for studying yeast sexuality mechanisms.