title: Purification of the pyruvate dehydrogenase multienzyme complex of Zymomonas mobilis and identification and sequence analysis of the corresponding genes.
abstract: The pyruvate dehydrogenase (PDH) complex of the gram-negative bacterium Zymomonas mobilis was purified to homogeneity. From 250 g of cells, we isolated 1 mg of PDH complex with a specific activity of 12.6 U/mg of protein. Analysis of subunit composition revealed a PDH (E1) consisting of the two subunits E1alpha (38 kDa) and E1beta (56 kDa), a dihydrolipoamide acetyltransferase (E2) of 48 kDa, and a lipoamide dehydrogenase (E3) of 50 kDa. The E2 core of the complex is arranged to form a pentagonal dodecahedron, as shown by electron microscopic images, resembling the quaternary structures of PDH complexes from gram-positive bacteria and eukaryotes. The PDH complex-encoding genes were identified by hybridization experiments and sequence analysis in two separate gene regions in the genome of Z. mobilis. The genes pdhAalpha (1,065 bp) and pdhAbeta (1,389 bp), encoding the E1alpha and E1beta subunits of the E1 component, were located downstream of the gene encoding enolase. The pdhB (1,323 bp) and lpd (1,401 bp) genes, encoding the E2 and E3 components, were identified in an unrelated gene region together with a 450-bp open reading frame (ORF) of unknown function in the order pdhB-ORF2-lpd. Highest similarities of the gene products of the pdhAalpha, pdhAbeta, and pdhB genes were found with the corresponding enzymes of Saccharomyces cerevisiae and other eukaryotes. Like the dihydrolipoamide acetyltransferases of S. cerevisiae and numerous other organisms, the product of the pdhB gene contains a single lipoyl domain. The E1beta subunit PDH was found to contain an amino-terminal lipoyl domain, a property which is unique among PDHs.
authors.affiliation: Institut für Biotechnologie, Forschungszentrum Jülich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Neveling
authors.forename: R
authors.initials: R
authors.lastname: Klasen
authors.forename: S
authors.initials: S
authors.lastname: Bringer-Meyer
authors.forename: H
authors.initials: H
authors.lastname: Sahm
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D008058:Dihydrolipoamide Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D005798:Genes, Bacterial; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics* / Q000302:isolation & purification* / Q000648:ultrastructure; D009693:Nucleic Acid Hybridization; D016366:Open Reading Frames; D010751:Phosphopyruvate Hydratase / Q000235:genetics; D010802:Phylogeny; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D030481:Pyruvate Dehydrogenase (Lipoamide); D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D017355:Zymomonas / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D009097:Multienzyme Complexes; D011768:Pyruvate Dehydrogenase Complex; D029701:Saccharomyces cerevisiae Proteins; D030481:Pyruvate Dehydrogenase (Lipoamide); C111305:pyruvate dehydrogenase E1 beta subunit; C065640:pyruvate dehydrogenase E1alpha subunit; D008058:Dihydrolipoamide Dehydrogenase; D000123:Acetyltransferases; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; C494879:LAT1 protein, S cerevisiae; D010751:Phosphopyruvate Hydratase