title: A biochemical correlate of dimorphism in a zygomycete Benjaminiella poitrasii: characterization of purified NAD-dependent glutamate dehydrogenase, a target for antifungal agents.
abstract: The fungal organisms, especially pathogens, change their vegetative (Y, unicellular yeast and H, hypha) morphology reversibly for survival and proliferation in the host environment. NAD-dependent glutamate dehydrogenase (NAD-GDH, EC 1.4.1.2) from a non-pathogenic dimorphic zygomycete Benjaminiella poitrasii was previously reported to be an important biochemical correlate of the transition process. The enzyme was purified to homogeneity and characterized. It is a 371 kDa native molecular weight protein made up of four identical subunits. Kinetic studies showed that unlike other NAD-GDHs, it may act as an anabolic enzyme and has more affinity towards 2-oxoglutarate than L-glutamate. Chemical modifications revealed the involvement of single histidine and lysine residues in the catalytic activity of the enzyme. The phosphorylation and dephosphorylation study showed that the NAD-GDH is present in active phosphorylated form in hyphal cells of B. poitrasii. Two of the 1,2,3 triazole linked β-lactam-bile acid conjugates synthesized in the laboratory (B18, B20) were found to be potent inhibitors of purified NAD-GDH which also significantly affected Y-H transition in B. poitrasii. Furthermore, the compound B20 inhibited germ tube formation during Y-H transition in Candida albicans strains and Yarrowia lipolytica. The possible use of NAD-GDH as a target for antifungal agents is discussed.
authors.affiliation: Biochemical Sciences Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India.
authors.forename: C V
authors.initials: CV
authors.lastname: Joshi
authors.forename: E K
authors.initials: EK
authors.lastname: Pathan
authors.forename: N S
authors.initials: NS
authors.lastname: Punekar
authors.forename: S G
authors.initials: SG
authors.lastname: Tupe
authors.forename: B P
authors.initials: BP
authors.lastname: Kapadnis
authors.forename: M V
authors.initials: MV
authors.lastname: Deshpande
mesh_terms: D000643:Ammonium Chloride / Q000378:metabolism; D000935:Antifungal Agents / Q000138:chemical synthesis / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure; D002384:Catalysis; D002847:Chromatography, Agarose; D004353:Drug Evaluation, Preclinical; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000187:drug effects; D025301:Hyphae / Q000201:enzymology; D007526:Isoelectric Point; D007656:Ketoglutaric Acids / Q000378:metabolism; D008239:Lysine / Q000737:chemistry / Q000187:drug effects; D058990:Molecular Targeted Therapy; D008970:Molecular Weight; D009090:Mucorales / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology / Q000648:ultrastructure; D009243:NAD / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D014230:Triazoles / Q000494:pharmacology; D025062:Yarrowia / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D007656:Ketoglutaric Acids; D014230:Triazoles; D000643:Ammonium Chloride; D009243:NAD; D018698:Glutamic Acid; D006639:Histidine; D005969:Glutamate Dehydrogenase; D008239:Lysine