4OLC

Carbamate kinase from Giardia lamblia thiocarbamoylated by disulfiram on Cys242

Summary for 4OLC

• Entry DOI: 10.2210/pdb4olc/pdb
• Related: 3KZF 4JZ7 4JZ8 4JZ9
• Descriptor: Carbamate kinase, CITRIC ACID, DIETHYLCARBAMODITHIOIC ACID, ... (4 entities in total)
• Functional Keywords: adp, mg2+, carbamate, carbamoyl phosphate, transferase
• Biological source: Giardia lamblia
• Total number of polymer chains: 4
• Total formula weight: 137117.21

Authors

Lim, K.,Herzberg, O. (deposition date: 2014-01-23, release date: 2014-02-26, Last modification date: 2024-10-16)

Primary citation

Galkin, A.,Kulakova, L.,Lim, K.,Chen, C.Z.,Zheng, W.,Turko, I.V.,Herzberg, O.
Structural Basis for Inactivation of Giardia lamblia Carbamate Kinase by Disulfiram.
J.Biol.Chem., 289:10502-10509, 2014

PubMed Abstract: Carbamate kinase from Giardia lamblia 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 G. lamblia CK and kills G. lamblia trophozoites in vitro at submicromolar IC50 values. Here, we examine the structural basis for G. lamblia CK 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 G. lamblia CK soaked with disulfiram revealed that the compound thiocarbamoylated Cys-242, a residue located at the edge of the active site. The modified Cys-242 prevents a conformational transition of a loop adjacent to the ADP/ATP binding site, which is required for the stacking of Tyr-245 side chain against the adenine moiety, an interaction seen in the structure of G. lamblia CK in complex with AMP-PNP. Mass spectrometry coupled with trypsin digestion confirmed the selective covalent thiocarbamoylation of Cys-242 in solution. The Giardia viability studies in the metronidazole-resistant strain and the G. lamblia CK 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 G. lamblia CK is an attractive drug target for development of novel antigiardial therapies and that disulfiram, an FDA-approved drug, is a promising candidate for drug repurposing.

PubMed: 24558036
DOI: 10.1074/jbc.M114.553123

Experimental method

X-RAY DIFFRACTION (2.6 Å)