Structural and kinetic differences between human and Aspergillus fumigatus D-glucosamine-6-phosphate N-acetyltransferase

Ramon Hurtado-Guerrero, Olawale G. Raimi, Jinrong Min, Hong Zeng, Laura Vallius, Sharon Shepherd, Adel F. M. Ibrahim, Hong Wu, Alexander N. Plotnikov, Daan M. F. van Aalten

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    15 Citations (Scopus)

    Abstract

    Aspergillus fumigatus is the causative agent of aspergillosis, a frequently invasive colonization of the lungs of immuno-compromised patients. GNA1 (D-glucosamine-6-phosphate N-acetyltransferase) catalyses the acetylation of GlcN-6P (glucosamine-6-phosphate) to GlcNAc-6P (N-acetylglucosamine-6-phosphate), a key intermediate in the UDP-GlcNAc biosynthetic pathway. Gene disruption of gnal in yeast and Candida albicans has provided genetic validation of the enzyme as a potential target. An understanding of potential active site differences between the human and A. fumigatus enzymes is required to enable further work aimed at identifying selective inhibitors for the fungal enzyme. In the present study, we describe crystal structures of both human and A. fumigatus GNA1, as well as their kinetic characterization. The structures show significant differences in the sugar-binding site with, in particular, several non-conservative substitutions near the phosphate-binding pocket. Mutagenesis targeting these differences revealed drastic effects on steady-state kinetics, suggesting that the differences could be exploitable with small-molecule inhibitors.

    Original languageEnglish
    Pages (from-to)217-223
    Number of pages7
    JournalBiochemical Journal
    Volume415
    DOIs
    Publication statusPublished - 15 Oct 2008

    Keywords

    • Aspergillus fumigatus
    • Inhibitor design
    • Kinetics
    • Mutagenesis
    • Protein structure
    • UDP-GlcNAc biosynthesis
    • X-ray crystallography
    • Glucosamine-6-phosphate acetyltransferase
    • Blastocladiella emersonii
    • Hexosamine biosynthesis
    • Invasive aspergillosis
    • Cell wall
    • Protein
    • Acetylglucosamine
    • Refinement
    • Therapy
    • Program

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