Download MendeleyThe post-reactive structures of Leishmania major UDP-sugar pyrophosphorylase provide insights into the product release mechanism.
Prakash, O., Fuhring, J., Baruch, P., Fedorov, R., Routier, F.H.(2025) Microbiol Spectr 13: e0091125-e0091125
- PubMed: 41070952 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1128/spectrum.00911-25
- Primary Citation Related Structures:
8TG2, 8TGS - PubMed Abstract:
Biosynthesis of the nucleotide sugars UDP-glucose (UDP-Glc) and UDP-galactose (UDP-Gal) is intimately connected and essential for the viability of trypanosomatid parasites. In the genus Leishmania , it is controlled by the UDP-glucose pyrophosphorylase (UGP) and UDP-sugar pyrophosphorylase (USP). In contrast to UGP, USP has a broad substrate specificity and may generate several UDP-sugars in vitro, including UDP-Glc and UDP-Gal. This enzyme, present in protozoan parasites (including Leishmania species and Trypanosoma cruzi ) and in plants, most likely plays a role in salvaging monosaccharides. In order to gain a detailed mechanistic understanding of USPs, we determined high-resolution X-ray structures of Leishmania major USP ( Lm USP) in post-reactive states. Several positions of the byproduct pyrophosphate (PP i ) were identified and revealed a product release channel in the forward reaction, as well as the geometries of post-reactive Michaelis product complexes. The conformational changes of functional loops (hinge loop-1, hinge loop-2, and the nucleotide-binding loop) showed dynamic effects accompanying the product release process. Structural information about the post-reactive states of Lm USP also includes the metastable binding position of a magnesium (Mg 2+ ) ion in the active site. The proposed product release mechanism was substantiated by molecular dynamics simulations and can serve as a model for other UDP-sugar pyrophosphorylases.IMPORTANCETo survive in the hostile environment of the sandfly gut, the parasite Leishmania relies on a range of phosphoglycans made of mannose-phosphate and galactose. In these glucose-limiting conditions, mannogen potentially serves as a reservoir for the synthesis of these crucial glycoconjugates, whereas galactose likely arises from recycling. The enzyme UDP-sugar pyrophosphorylase (USP) is responsible for the activation of this monosaccharide. This enzyme has a relaxed specificity and converts UTP and a range of sugar-1-phosphate to the corresponding UDP-sugar and pyrophosphate (PP i ). Here, we determined high-resolution X-ray structures of Leishmania major USP ( Lm USP) in post-reactive states. The data provide insight into the product release mechanism for UDP-sugar pyrophosphorylases. Considering the conservation of the residues involved in the coordination of PP i amongst USP enzymes, this mechanism is relevant for all USPs. This work completes our knowledge of the catalytic mechanism of trypanosomatid uridylyltransferases, which are genetically validated drug targets.
- Institute for Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
Organizational Affiliation:
