4olc | pdb_00004olc

Carbamate kinase from Giardia lamblia thiocarbamoylated by disulfiram on Cys242

spinqualitylabelsall models 4olc, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4olc is a 4 chain structure with sequence from Giardia lamblia ATCC 50803. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CIT, DCD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A8BB85_GIAIC Publication Abstract from PubMed Carbamate kinase from Giardia lamblia (glCK1) is an essential enzyme for the survival of the organism. The enzyme catalyzes the final step in the arginine dihydrolase pathway converting ADP and carbamoyl phosphate to ATP and carbamate. We previously reported that disulfiram, a drug used to treat chronic alcoholism, inhibits glCK and kills G. lamblia trophozoites in vitro at submicromolar IC50 values. Here we examine the structural basis for glCK inhibition of disulfiram and its analog, thiram, their activities against both metronidazole-susceptible and metronidazole-resistant G. lamblia isolates, and their efficacy in a mouse model of Giardiasis. The crystal structure of glCK soaked with disulfiram revealed that the compound thiocarbamoylated Cys242, a residue located at the edge of the active site. The modified Cys242 prevents a conformational transition of a loop adjacent to the ADP/ATP binding site, which is required for the stacking of Tyr245 side chain against the adenine moiety, an interaction seen in the structure of glCK in complex with AMP-PNP. Mass spectrometry coupled with trypsin digestion confirmed the selective covalent thiocarbamoylation of Cys242 in solution. The G. lamblia viability studies in the metronidazole-resistant strain and the glCK irreversible inactivation mechanism show that the thiuram compounds can circumvent the resistance mechanism that renders metronidazole ineffectiveness in drug resistance cases of giardiasis. Together, the studies suggest that glCK is an attractive drug target for development of novel antigiardial therapies, and that disulfiram, a FDA approved drug, is a promising candidate for drug repurposing. Structural Basis for Inactivation of Giardia lamblia Carbamate Kinase by Disulfiram.,Galkin A, Kulakova L, Lim K, Chen CZ, Zheng W, Turko IV, Herzberg O J Biol Chem. 2014 Feb 20. PMID:24558036 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Proteopedia Page Contributors and Editors (what is this?)

OCA