Structural and kinetic differences between human and Aspergillus fumigatus D-glucosamine-6-phosphate N-acetyltransferase.
Aspergillus fumigatus is the causative agent of aspergillosis, a frequently invasive colonization of the lungs of immunocompromised 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 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. 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.
Hurtado-Guerrero
Ramon
R
Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Raimi
Olawale G
OG
Min
Jinrong
J
Zeng
Hong
H
Vallius
Laura
L
Shepherd
Sharon
S
Ibrahim
Adel F M
AF
Wu
Hong
H
Plotnikov
Alexander N
AN
van Aalten
Daan M F
DM
D000595:Amino Acid Sequence; D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051081:Glucosamine 6-Phosphate N-Acetyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; D051081:Glucosamine 6-Phosphate N-Acetyltransferase