The interaction between fructose-1,6-bisphosphate aldolase and glyceraldehyde-3-phosphate dehydrogenase regulates redox processes linked to methylglyoxal biosynthesis.

Candida albicans glutathione reductase-overexpressing mutant (GLR1OE) 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. FBA1OE 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, FBA1OE 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 FBA1OE, which differs significantly from GLR1OE 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.