The complex fate of alpha-ketoacids.
Plant cells are unique in that they contain four species of alpha-ketoacid dehydrogenase complex: plastidial pyruvate dehydrogenase, mitochondrial pyruvate dehydrogenase, alpha-ketoglutarate (2-oxoglutarate) dehydrogenase, and branched-chain alpha-ketoacid dehydrogenase. All complexes include multiple copies of three components: an alpha-ketoacid dehydrogenase/decarboxylase, a dihydrolipoyl acyltransferase, and a dihydrolipoyl dehydrogenase. The mitochondrial pyruvate dehydrogenase complex additionally includes intrinsic regulatory protein-kinase and -phosphatase enzymes. The acyltransferases form the intricate geometric core structures of the complexes. Substrate channeling plus active-site coupling combine to greatly enhance the catalytic efficiency of these complexes. These alpha-ketoacid dehydrogenase complexes occupy key positions in intermediary metabolism, and a basic understanding of their properties is critical to genetic and metabolic engineering. The current status of knowledge of the biochemical, regulatory, structural, genomic, and evolutionary aspects of these fascinating multienzyme complexes are reviewed.
Mooney
Brian P
BP
Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA. mooneyb@missouri.edu
Miernyk
Jan A
JA
Randall
Douglas D
DD
D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000143:Acids / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007658:Ketone Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D010944:Plants / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000201:enzymology; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry / Q000378:metabolism
D000143:Acids; D009097:Multienzyme Complexes; D011768:Pyruvate Dehydrogenase Complex; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)