Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although coenzymeA (CoA) is essential in numerous metabolic pathways in all living cells, molecular characterization of the CoA biosynthetic pathway in Archaea remains undocumented. Archaeal genomes contain detectable homologues for only three of the five steps of the CoA biosynthetic pathway characterized in Eukarya and Bacteria. In case of phosphopantetheine adenylyltransferase (PPAT) (EC 2.7.7.3), the putative archaeal enzyme exhibits significant sequence similarity only with its eukaryotic homologs, an unusual situation for a protein involved in a central metabolic pathway. We have overexpressed in Escherichia coli, purified, and characterized this putative PPAT from the hyperthermophilic archaeon Pyrococcus abyssi (PAB0944). Matrix-assisted laser desorption ionization-time of flight mass spectrometry and high performance liquid chromatography measurements are consistent with the presence of a dephospho-CoA (dPCoA) molecule tightly bound to the polypeptide. The protein indeed catalyzes the synthesis of dPCoA from 4'-phosphopantetheine and ATP, as well as the reverse reaction. The presence of dPCoA stabilizes PAB0944, as it induces a shift from 76 to 82 degrees C of the apparent Tm measured by differential scanning microcalorimetry. Potassium glutamate was found to stabilize the protein at 400 mm. The enzyme behaves as a monomeric protein. Although only distantly related, secondary structure prediction indicates that archaeal and eukaryal PPAT belong to the same nucleotidyltransferase superfamily of bacterial PPAT. The existence of operational proteins highly conserved between Archaea and Eukarya involved in a central metabolic pathway challenge evolutionary scenarios in which eukaryal operational proteins are strictly of bacterial origin.
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PMID:Identification, purification, and characterization of an eukaryotic-like phosphopantetheine adenylyltransferase (coenzyme A biosynthetic pathway) in the hyperthermophilic archaeon Pyrococcus abyssi. 1275 45

The penultimate step of prokaryotic coenzyme A (CoA) biosynthesis is directed by the essential enzyme phosphopantetheine adenylyltransferase (PPAT; EC 2.7.7.3), an attractive target for antibiotics. The reaction catalyzed by PPAT is rate-limiting and involves the transfer of an adenylyl group from ATP to 4'-phosphopantetheine to form 3'-dephospho-CoA. Rhombohedral crystals of PPAT from Mycobacterium tuberculosis (Rv2965c) were obtained. The crystals belong to space group R32, with unit-cell parameters a = 68.69 A, alpha = 91.81 degrees. The crystals diffract to better than 2 A resolution on a Cu Kalpha rotating-anode generator. The packing density for one polypeptide chain in the asymmetric unit is 2.89 A(3) Da(-1), with a solvent content of 0.57.
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PMID:Rhombohedral crystals of Mycobacterium tuberculosis phosphopantetheine adenylyltransferase. 1468 28