title: High resolution crystal structure of Clostridium propionicum β-alanyl-CoA:ammonia lyase, a new member of the "hot dog fold" protein superfamily.
abstract: Clostridium propionicum is the only organism known to ferment β-alanine, a constituent of coenzyme A (CoA) and the phosphopantetheinyl prosthetic group of holo-acyl carrier protein. The first step in the fermentation is a CoA-transfer to β-alanine. Subsequently, the resulting β-alanyl-CoA is deaminated by the enzyme β-alanyl-CoA:ammonia lyase (Acl) to reversibly form ammonia and acrylyl-CoA. We have determined the crystal structure of Acl in its apo-form at a resolution of 0.97 Å as well as in complex with CoA at a resolution of 1.59 Å. The structures reveal that the enyzme belongs to a superfamily of proteins exhibiting a so called "hot dog fold" which is characterized by a five-stranded antiparallel β-sheet with a long α-helix packed against it. The functional unit of all "hot dog fold" proteins is a homodimer containing two equivalent substrate binding sites which are established by the dimer interface. In the case of Acl, three functional dimers combine to a homohexamer strongly resembling the homohexamer formed by YciA-like acyl-CoA thioesterases. Here, we propose an enzymatic mechanism based on the crystal structure of the Acl·CoA complex and molecular docking.
authors.affiliation: Institut für Pharmazeutische Chemie, Fachbereich Pharmazie, Philipps-Universität Marburg, Marbacher Weg 6, D-35032, Marburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Heine
authors.forename: Gloria
authors.initials: G
authors.lastname: Herrmann
authors.forename: Thorsten
authors.initials: T
authors.lastname: Selmer
authors.forename: Felix
authors.initials: F
authors.lastname: Terwesten
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Buckel
authors.forename: Klaus
authors.initials: K
authors.lastname: Reuter
mesh_terms: D000595:Amino Acid Sequence; D000642:Ammonia-Lyases / Q000648:ultrastructure*; D001665:Binding Sites; D003013:Clostridium / Q000201:enzymology*; D003065:Coenzyme A / Q000378:metabolism; D018360:Crystallography, X-Ray; D005285:Fermentation / Q000502:physiology; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D015091:beta-Alanine / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D015091:beta-Alanine; D000642:Ammonia-Lyases; D003065:Coenzyme A
keywords: YciA; ammonia lyase; lysine fermentation; syn-elimination; zinc phasing