A Saccharomyces cerevisiae mutant lacking a K+/H+ exchanger

Area of Science:

• Molecular biology
• Yeast genetics
• Cell physiology

Background:

• The KHA1 gene in Saccharomyces cerevisiae encodes a putative potassium/hydrogen (K+/H+) antiporter.
• This protein shares similarities with known antiporter proteins in other bacterial species.

Purpose of the Study:

• To investigate the function of the KHA1 gene by disrupting it in Saccharomyces cerevisiae.
• To understand the role of KHA1 in potassium transport, cell growth, and metabolism.

Main Methods:

• Homologous recombination was used to disrupt the KHA1 gene.
• Flow cytometry was employed to analyze DNA duplication rates.
• 86Rubidium (86Rb+) uptake assays were conducted to study potassium transport kinetics.
• Measurements of medium acidification, internal pH, and oxygen consumption were performed.

Main Results:

• KHA1 gene disruption led to increased intracellular potassium accumulation and net influx.
• Mutant strains exhibited enhanced growth rates, smaller cell size, and doubled cell yield per glucose.
• Increased DNA duplication rate, medium acidification, internal pH alkalinization, and higher oxygen consumption velocity were observed.
• Potassium transport kinetics remained similar between wild-type and mutant strains.

Conclusions:

• The KHA1 gene product is a functional K+/H+ antiporter in yeast.
• Increased intracellular potassium accumulation and osmotic pressure likely accelerate the cell cycle and metabolic activity.
• KHA1 disruption significantly impacts yeast physiology, offering insights into nutrient transport and cell growth regulation.