Sporothrix schenckii: purification and partial biochemical characterization of glucosamine-6-phosphate synthase, a potential antifungal target.

Med Mycol 2010 Feb;48(1):110-21

Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Gto, México.

The first committed step of the biosynthetic pathway leading to uridine-5'-diphospho-N-acetyl-D-glucosamine (UDP-GlcNAc) is catalyzed by glucosamine-6-phosphate synthase (GlcN-6-P synthase), an enzyme proposed as a potential antifungal chemotherapy target. Here, we describe the purification and biochemical characterization of the native enzyme from the dimorphic pathogenic fungus Sporothrix schenckii. The availability of the pure protein facilitated its biochemical characterization. The enzyme exhibited subunit and native molecular masses of 79 and 350+/-5 kDa, respectively, suggesting a homotetrameric structure. Isoelectric point was 6.26 and K(m) values for fructose-6-phosphate and L-glutamine were 1.12+/-0.3 and 2.2+/-0.7 mM, respectively. Inhibition of activity by UDP-GlcNAc was enhanced by Glc-6-P and phosphorylation stimulated GlcN-6-P synthase activity without affecting the enzyme sensitivity to the aminosugar. A glutamine analogue, FMDP [N(3)-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid] was a more potent inhibitor of activity than ADMP (2-Amino-2-deoxy-D-mannitol-6-phosphate) but the latter was a stronger inhibitor of growth in two culture media. To our knowledge, this is the first report on the purification and biochemical characterization of a non-recombinant GlcN-6-P synthase from a true dimorphic fungus. Inhibition of enzyme activity and fungal growth by specific inhibitors of GlcN-6-P synthase strongly reinforces the role of this enzyme as a potential target for antifungal chemotherapy.

Download full-text PDF

Source
http://dx.doi.org/10.3109/13693780902856030DOI Listing
February 2010

Publication Analysis

Top Keywords

glcn-6-p synthase
16
biochemical characterization
16
potential antifungal
8
antifungal chemotherapy
8
glucosamine-6-phosphate synthase
8
purification biochemical
8
sporothrix schenckii
8
enzyme
6
synthase
6
phosphorylation stimulated
4
glc-6-p phosphorylation
4
activity udp-glcnac
4
udp-glcnac enhanced
4
enhanced glc-6-p
4
stimulated glcn-6-p
4
activity enzyme
4
glutamine analogue
4
analogue fmdp
4
aminosugar glutamine
4
sensitivity aminosugar
4

Similar Publications