Roles of fructose-1,6-bisphosphate aldolase in Candida albicans

Abstract

Fructose-1,6-bisphosphate aldolase is one of the important glycolytic enzyme which catalyzes the reversible conversion of a fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate required for both glycolysis and gluconeogenesis. Herein, the gene encoding fructose-1,6-bisphosphate aldolase (FBA1) has been cloned from Candida albicans. The FBA1 gene contained an open reading frame consisted of 1,080 bp that encodes a polypeptide consisting of 360 amino acids with a calculated molecular mass of 39,215 Da. To investigate the functional role of FBA1 in C. albicans, the FBA1 gene was disrupted or overexpressed. The fba1/fba1 null mutants were not viable in both rich and minimally defined medium. The FBA1/fab1 heterozygous mutant exhibited the significant decreased RNA profile of FBA1 contrast to the wild-type cells (FBA1/FBA1), significantly. However, the phenotypes in terms of the differentiation in FBA1/fab1 heterozygous mutant displayed no difference compared to wild-type cells. However, the FBA1-overexpressing cells led to the morphological transition into true hyphae in glucose-containing rich medium, and true hyphal-specific gene HWP1 was remarkably expressed through the northern blot analysis. Additionally, the intracellular methylglyoxal and reactive oxygen species concentrations were increased while the glutathione level was decreased inversely proportional to those of FBA1-overexpressing cells. This result suggests that the FBA1 overexpression of C. albicans might lead to methylglyoxal accumulation in cells, significantly. Moreover, FBA1-overpexpressing cells underwent to G1-phase arrest of the cell cycle due to the methylglyoxal accumulation, which led to the formation of true hyphae. Therefore, Candida albicans fructose-1,6-bisphosphate aldolase overexpression caused to methylglyoxal accumulation leading to altered cell growth, differentiation and the cell cycle.