Structural basis for transport and inhibition of nucleotide sugar transport in pathogenic fungi

GDP-Mannose transporters are Golgi-localised solute carriers that are essential for the virulence of pathogenic fungi, serving as critical components of fungal glycosylation pathways. However, the mechanism by which nucleotide sugars are recognised and transported across the Golgi membrane remains unclear, hindering efforts to develop effective inhibitors that could serve as novel antifungal agents. Here, we present cryo-EM structures of the GDP-Mannose transporter, Vrg4, from Candida albicans in complex with nanobodies and in both the cytoplasmic and Golgi-facing states. Structural comparisons between these two states, in addition to a GDP-mannose bound structure, demonstrate the importance of ligand movement during transport. Additionally, we demonstrate the ability of the nanobodies to specifically inhibit Vrg4, presenting proof-of-principle that nanobodies can be used as effective inhibitors of nucleotide sugar transport and glycosylation in cells.