X-ray structure and characterization of carbamate kinase from the human parasite Giardia lamblia.

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TitleX-ray structure and characterization of carbamate kinase from the human parasite Giardia lamblia.
Publication TypeJournal Article
Year of Publication2010
AuthorsGalkin, A, Kulakova, L, Wu, R, Nash, TE, Dunaway-Mariano, D, Herzberg, O
JournalActa Crystallogr Sect F Struct Biol Cryst Commun
IssuePt 4
Date Published2010 Apr 1
KeywordsCarbamyl Phosphate, Catalytic Domain, Crystallography, X-Ray, Giardia lamblia, Glycerol, Models, Molecular, Phosphotransferases (Carboxyl Group Acceptor), Protein Structure, Quaternary, Structural Homology, Protein

Carbamate kinase catalyzes the reversible conversion of carbamoyl phosphate and ADP to ATP and ammonium carbamate, which is hydrolyzed to ammonia and carbonate. The three-dimensional structure of carbamate kinase from the human parasite Giardia lamblia (glCK) has been determined at 3 A resolution. The crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 69.77, b = 85.41, c = 102.1 A, beta = 106.8 degrees . The structure was refined to a final R factor of 0.227. The essentiality of glCK together with its absence in humans makes the enzyme an attractive candidate for anti-Giardia drug development. Steady-state kinetic rate constants have been determined. The k(cat) for ATP formation is 319 +/- 9 s(-1). The K(m) values for carbamoyl phosphate and ADP are 85 +/- 6 and 70 +/- 5 microM, respectively. The structure suggests that three invariant lysine residues (Lys131, Lys216 and Lys278) may be involved in the binding of substrates and phosphoryl transfer. The structure of glCK reveals that a glycerol molecule binds in the likely carbamoyl phosphate-binding site.

Alternate JournalActa Crystallogr. Sect. F Struct. Biol. Cryst. Commun.
PubMed ID20383005
PubMed Central IDPMC2852327
Grant ListR01 AI059733 / AI / NIAID NIH HHS / United States