Pathogenic Candida species differ in the ability to grow at limiting potassium concentrations

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• High intracellular potassium (200-300 mmol/L) is crucial for yeast cell functions like volume and pH regulation, membrane potential, and enzyme activation.
• Yeast cells actively transport potassium using specific high-affinity systems, requiring significant energy.
• Three types of putative potassium uptake systems (Trk uniporters, Hak symporters, Acu ATPases) have been identified in Candida genomes.

Purpose of the Study:

• To investigate the tolerance and sensitivity of various Candida species to different potassium concentrations.
• To explore the impact of external pH on potassium tolerance in Candida species.
• To assess the influence of potassium availability on Candida cell morphology.

Main Methods:

• Comparative analysis of potassium tolerance and sensitivity across six Candida species (C. albicans, C. dubliniensis, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis).
• Evaluation of the effects of varying external potassium concentrations and pH levels on Candida growth and morphology.
• Identification and characterization of putative potassium uptake systems in Candida genomes.

Main Results:

• Significant interspecies differences in potassium tolerance were observed, partly influenced by external pH.
• Candida albicans and Candida krusei exhibited the highest tolerance to potassium-limiting conditions.
• Candida parapsilosis tolerated the highest external KCl concentrations, and cell morphology was most affected in C. krusei and C. tropicalis.

Conclusions:

• Potassium uptake and accumulation are critical for Candida cell growth.
• The Trk1 potassium uptake system, which is the sole system in C. krusei and C. glabrata, represents a potential target for novel antifungal drug development.