Carbonic anhydrases in fungi

Carbonic anhydrases (CAs) are metalloenzymes that catalyse the interconversion of carbon dioxide and bicarbonate with high efficiency. This reaction is fundamental to biological processes such as respiration, photosynthesis, pH homeostasis, CO2 transport and electrolyte secretion. CAs are distributed among all three domains of life, and are currently divided into five evolutionarily unrelated classes (alpha, beta, gamma, delta and zeta). Fungal CAs have only recently been identified and characterized in detail. While Saccharomyces cerevisiae and Candida albicans each have only one beta-CA, multiple copies of beta-CA- and alpha-CA-encoding genes are found in other fungi. Recent work demonstrates that CAs play an important role in the CO2-sensing system of fungal pathogens and in the regulation of sexual development. This review focuses on CA functions in S. cerevisiae, the fungal pathogens C. albicans and Cryptococcus neoformans, and the filamentous ascomycete Sordaria macrospora.