title: Discovering new enzymes and metabolic pathways: conversion of succinate to propionate by Escherichia coli.
abstract: The Escherichia coli genome encodes seven paralogues of the crotonase (enoyl CoA hydratase) superfamily. Four of these have unknown or uncertain functions; their existence was unknown prior to the completion of the E. coli genome sequencing project. The gene encoding one of these, YgfG, is located in a four-gene operon that encodes homologues of methylmalonyl CoA mutases (Sbm) and acyl CoA transferases (YgfH) as well as a putative protein kinase (YgfD/ArgK). We have determined that YgfG is methylmalonyl CoA decarboxylase, YgfH is propionyl CoA:succinate CoA transferase, and Sbm is methylmalonyl CoA mutase. These reactions are sufficient to form a metabolic cycle by which E. coli can catalyze the decarboxylation of succinate to propionate, although the metabolic context of this cycle is unknown. The identification of YgfG as methylmalonyl CoA decarboxylase expands the range of reactions catalyzed by members of the crotonase superfamily.
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: T
authors.initials: T
authors.lastname: Haller
authors.forename: T
authors.initials: T
authors.lastname: Buckel
authors.forename: J
authors.initials: J
authors.lastname: Rétey
authors.forename: J A
authors.initials: JA
authors.lastname: Gerlt
mesh_terms: D000595:Amino Acid Sequence; D002262:Carboxy-Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D003001:Cloning, Molecular; D003038:Cobamides / Q000378:metabolism; D015256:Coenzyme A-Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004746:Enoyl-CoA Hydratase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics / Q000502:physiology; D016680:Genome, Bacterial; D007700:Kinetics; D043586:Methylmalonyl-CoA Decarboxylase; D008765:Methylmalonyl-CoA Mutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D009876:Operon / Q000235:genetics / Q000502:physiology; D011422:Propionates / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019998:Racemases and Epimerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D003038:Cobamides; D011422:Propionates; D019802:Succinic Acid; D011494:Protein Kinases; D015256:Coenzyme A-Transferases; C022694:succinyl CoA propionate CoA-transferase; D002262:Carboxy-Lyases; D004746:Enoyl-CoA Hydratase; D019998:Racemases and Epimerases; C021581:methylmalonyl-coenzyme A racemase; D008765:Methylmalonyl-CoA Mutase; D043586:Methylmalonyl-CoA Decarboxylase; C000913:cobamamide; C029658:propionic acid