Characterization of the Bifunctional Enzyme BioDA Involved in Biotin Synthesis and Pathogenicity in .

Biotin is an important enzyme cofactor that plays a key role in all three domains. The classical bifunctional enzyme BioDA in eukaryotes (such as and ) is involved in the antepenultimate and penultimate steps of biotin biosynthesis. In this study, we identified a bifunctional gene which could complement both Δ and Δ mutants. Interestingly, the separated domain of AfBioD and AfBioA could, respectively, fuse with EcBioA and EcBioD well and work together. What is more, we found that BioDA was almost localized to the mitochondria in , as shown by N-terminal red fluorescent protein tag fusion. Noteworthy, the subcellular localization of AfBioDA is never affected by common environmental stresses (such as hyperosmotic stress or oxidative stress). The knockout strategy demonstrated that the deletion of gene from the chromosome impaired the biotin synthesis pathway in . Importantly, this mutant blocked biotin production and decreased its pathogenicity to infect peanuts. Based on the structural comparison, we found that two inhibitors (amiclenomycin and gemcitabine) could be candidates for antifungal drugs. Taken together, our findings identified the bifunctional gene and shed light on biotin biosynthesis in .