The interaction between fructose-1,6-bisphosphate aldolase and glyceraldehyde-3-phosphate dehydrogenase regulates...

Candida albicans glutathione reductase-overexpressing mutant (GLR1^OE) exhibits increased expression of fructose-1,6-bisphosphate aldolase (FBA1), glyceraldehyde-3-phosphate dehydrogenase (TDH3), and alcohol dehydrogenase (ADH1). To investigate the effect of FBA1 overexpression on methylglyoxal biosynthesis-linked redox regulation, we modeled how the interaction between Fba1 and Tdh3 influences redox-related metabolic processes under different carbon sources. FBA1^OE induced a redox imbalance in a hypha-inducing medium, evidenced by decreased in methylglyoxal levels and an increased glutathione content. These changes coincided with defects in proliferation and filamentation. Furthermore, FBA1^OE caused inconsistent metabolic flux between Glr1 activity and glutathione content, independent of distinct differentiation/proliferation patterns. The data suggest a parallel mechanism between redox regulation and hyphal pathogenicity in FBA1^OE, which differs significantly from GLR1^OE differentiation/proliferation governed by glutathione-linked metabolic redox regulation. This evidence offers additional insight into physio-metabolic alterations that may arise from protein-protein interactions (PPIs) mediated by methylglyoxal-induced Fba1 activity, independent of glutathione and carbon source. Ligand fishing and co-immunoprecipitation consistently identified Tdh3 as a major partner of Fba1. Purified Fba1-Tdh3 complexes more effectively inhibited methylglyoxal production than reactions lacking the complex, shifting the substrate fructose-1,6-bisphosphate equilibrium away from methylglyoxal accumulation. Network-based analysis revealed that Fba1 features a corridor of three hotspot patches that engage Tdh3 β-strands and loops through a mixed hydrophobic and polar network stabilized by hydrogen bonds and salt bridges, reminiscent of adhesion interfaces. Our study identified the Fba1-Tdh3 complex as a redox-sensitive, adhesion-type interface that links methylglyoxal detoxification to C. albicans redox homeostasis. This complex offers a structurally defined target for designing antifungal PPIs inhibitors.