Structural and kinetic differences between human and Aspergillus fumigatus glucosamine N-acetyl transferase

Ramon Hurtado-Guerrero , Olawale G. Raimi , Jinrong Ming , Hong Zeng , Laura Vallius , Sharon M. Shepherd , Adel F.M. Ibrahim , Hong Wu , Alexander Plotnikov , Daan Mf van Aalten (1)

1 Wellcome Trust Biocentre,

Aspergillus fumigatus is the causative agent of aspergillosis, a frequently invasive colonisation of the lungs of immunocompromised patients. Glucosamine-6-phosphate N-acetyltransferase (GNA1) catalyses the acetylation of glucosamine-6-phosphate (GlcN-6P) to N-acetylglucosamine-6-phosphate (GlcNAc-6P), a key intermediate in the UDP-GlcNAc biosynthetic pathway. Gene disruption of gna1 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. Here, 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.

Mots clés: Life Sciences

Ramon Hurtado-Guerrero, Olawale G. Raimi, Jinrong Ming, Hong Zeng, Laura Vallius, et al.. Structural and kinetic differences between human and Aspergillus fumigatus glucosamine N-acetyl transferase. Biochemical Journal, 2008, 415 (2), pp.217-223. ⟨10.1042/BJ20081000⟩. ⟨hal-00479028⟩