title: Crystal structure of a trimeric form of dephosphocoenzyme A kinase from Escherichia coli.
abstract: Coenzyme A (CoA) is an essential cofactor used in a wide variety of biochemical pathways. The final step in the biosynthesis of CoA is catalyzed by dephosphocoenzyme A kinase (DPCK, E.C. 2.7.1.24). Here we report the crystal structure of DPCK from Escherichia coli at 1.8 A resolution. This enzyme forms a tightly packed trimer in its crystal state, in contrast to its observed monomeric structure in solution and to the monomeric, homologous DPCK structure from Haemophilus influenzae. We have confirmed the existence of the trimeric form of the enzyme in solution using gel filtration chromatography measurements. Dephospho-CoA kinase is structurally similar to many nucleoside kinases and other P-loop-containing nucleotide triphosphate hydrolases, despite having negligible sequence similarity to these enzymes. Each monomer consists of five parallel beta-strands flanked by alpha-helices, with an ATP-binding site formed by a P-loop motif. Orthologs of the E. coli DPCK sequence exist in a wide range of organisms, including humans. Multiple alignment of orthologous DPCK sequences reveals a set of highly conserved residues in the vicinity of the nucleotide/CoA binding site.
authors.affiliation: Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6, Canada.
authors.forename: Nicholas
authors.initials: N
authors.lastname: O'Toole
authors.forename: João A R G
authors.initials: JA
authors.lastname: Barbosa
authors.forename: Yunge
authors.initials: Y
authors.lastname: Li
authors.forename: Li-Wei
authors.initials: LW
authors.lastname: Hung
authors.forename: Allan
authors.initials: A
authors.lastname: Matte
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Cygler
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006193:Haemophilus influenzae / Q000201:enzymology; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029968:Escherichia coli Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C020021:dephospho-CoA kinase