Chromosomal mutants of Saccharomyces cerevisiae affecting the cell wall binding site for killer factor

Area of Science:

• Molecular Biology
• Yeast Genetics
• Cell Wall Biology

Background:

• Yeast killer factors are toxins produced by certain yeast strains.
• Resistance to killer factors is crucial for yeast strain survival and application.
• The specific mechanisms of killer factor resistance are not fully understood.

Purpose of the Study:

• To isolate and characterize yeast mutants resistant to killer factor.
• To identify the genetic and molecular basis of killer resistance in yeast.
• To elucidate the nature of the killer factor binding site on the yeast cell wall.

Main Methods:

• Isolation of 52 killer factor-resistant, nuclear mutants from sensitive yeast strains.
• Functional grouping of mutants based on resistance phenotypes.
• Analysis of cell wall properties, including susceptibility to glusulase and inactivation of the killer binding site by periodate and pronase.

Main Results:

• Fifty-two resistant mutants were isolated and classified into three functional groups.
• Resistance in all but one mutant was attributed to alterations in the cell wall killer binding site.
• Changes at the binding site correlated with altered cell wall susceptibility to glusulase and could be inactivated by periodate but not pronase.

Conclusions:

• The yeast cell wall binding site is the primary target for killer factor resistance.
• Alterations in this site affect cell wall integrity and susceptibility to enzymatic degradation.
• The killer binding site is likely composed of carbohydrate moieties sensitive to periodate oxidation.