title: X-ray structure determination at 2.6-A resolution of a lipoate-containing protein: the H-protein of the glycine decarboxylase complex from pea leaves.
abstract: H-protein, a lipoic acid-containing protein of the glycine decarboxylase (EC 1.4.4.2) complex from pea (Pisum sativum) was crystallized from ammonium sulfate solution at pH 5.2 in space group P3(1)21. The x-ray crystal structure was determined to 2.6-A resolution by multiple isomorphous replacement techniques. The structure was refined to an R value of 23% for reflections between 15- and 2.6-A resolution (F > 2 sigma), including the lipoate moiety and 50 water molecules, for the two protein molecules of the asymmetric unit. The 131-amino acid residues form seven beta-strands arranged into two antiparallel beta-sheets forming a "sandwich" structure. One alpha-helix is observed at the C-terminal end. The lipoate cofactor attached to Lys-63 is located in the loop of a hairpin configuration. The lipoate moiety points toward the residues His-34 and Asp-128 and is situated at the surface of the H-protein. This allows the flexibility of the lipoate arm. This is the first x-ray determination of a lipoic acid-containing protein, and the present results are in agreement with previous theoretical predictions and NMR studies of the catalytic domains of lipoic acid- and biotin-containing proteins.
authors.affiliation: Institut de Biologie Structurale, Centre National de la Recherche Scientifique et Commissariat à l'Energie Atomique, Grenoble, France.
authors.forename: S
authors.initials: S
authors.lastname: Pares
authors.forename: C
authors.initials: C
authors.lastname: Cohen-Addad
authors.forename: L
authors.initials: L
authors.lastname: Sieker
authors.forename: M
authors.initials: M
authors.lastname: Neuburger
authors.forename: R
authors.initials: R
authors.lastname: Douce
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007887:Fabaceae / Q000737:chemistry*; D050959:Glycine Decarboxylase Complex; D050961:Glycine Decarboxylase Complex H-Protein; D050841:Glycine Dehydrogenase (Decarboxylating); D006801:Humans; D008969:Molecular Sequence Data; D010946:Plants, Medicinal; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D008063:Thioctic Acid / Q000737:chemistry*
chemical_list: D002352:Carrier Proteins; D050961:Glycine Decarboxylase Complex H-Protein; D008063:Thioctic Acid; D000594:Amino Acid Oxidoreductases; D050959:Glycine Decarboxylase Complex; D050841:Glycine Dehydrogenase (Decarboxylating)