1b6t
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PHOSPHOPANTETHEINE ADENYLYLTRANSFERASE IN COMPLEX WITH 3'-DEPHOSPHO-COA FROM ESCHERICHIA COLI
OverviewOverview
Phosphopantetheine adenylyltransferase (PPAT) is an essential enzyme in, bacteria that catalyses a rate-limiting step in coenzyme A (CoA), biosynthesis, by transferring an adenylyl group from ATP to, 4'-phosphopantetheine, yielding dephospho-CoA (dPCoA). Each, phosphopantetheine adenylyltransferase (PPAT) subunit displays a, dinucleotide-binding fold that is structurally similar to that in class I, aminoacyl-tRNA synthetases. Superposition of bound adenylyl moieties from, dPCoA in PPAT and ATP in aminoacyl-tRNA synthetases suggests nucleophilic, attack by the 4'-phosphopantetheine on the alpha-phosphate of ATP. The, proposed catalytic mechanism implicates transition state stabilization by, PPAT without involving functional groups of the enzyme in a chemical sense, in the reaction. The crystal structure of the enzyme from Escherichia coli, in complex with dPCoA shows that binding at one site causes a vice-like, movement of active site residues lining the active site surface. The mode, of enzyme product formation is highly concerted, with only one trimer of, the PPAT hexamer showing evidence of dPCoA binding. The homologous active, site attachment of ATP and the structural distribution of predicted, sequence-binding motifs in PPAT classify the enzyme as belonging to the, nucleotidyltransferase superfamily.
About this StructureAbout this Structure
1B6T is a Single protein structure of sequence from Escherichia coli with SO4 and COD as ligands. Active as Pantetheine-phosphate adenylyltransferase, with EC number 2.7.7.3 Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of a novel bacterial adenylyltransferase reveals half of sites reactivity., Izard T, Geerlof A, EMBO J. 1999 Apr 15;18(8):2021-30. PMID:10205156
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