title: Homology modeling of adenylosuccinate synthetase from Saccharomyces cerevisiae reveals a possible binding region for single-stranded ARS sequences.
abstract: Adenylosuccinate synthetase from Saccharomyces cerevisiae was investigated in order to find a structural explanation for its ability to bind specifically to single-stranded ARS elements (autonomously replicating sequences). Using the E. coli enzyme as template, a model for the structure of adenylosuccinate synthetase from S. cerevisiae was generated and subsequently refined by molecular dynamics techniques. The resulting three-dimensional structure offers an explanation for the DNA binding activity of the yeast enzyme by revealing a distinct basic region that is not present in the homologous enzymes from other organisms. The model is also in good agreement with biochemical data available for a mutant protein in which Glycine 252 is replaced by Aspartate. On the basis of the model a significant structural distortion near the catalytic center was predicted for this mutant, corresponding well to the enzymatic inactivity observed. The mutant enzyme shows larger structural fluctuations than the wild-type protein according to the results of two independent molecular dynamics simulations.
authors.affiliation: Lehrstuhl für Struktur und Chemie der Biopolymere, Universität Bayreuth, Germany. Heinrich.Sticht@uni-bayreuth.de
authors.forename: H
authors.initials: H
authors.lastname: Sticht
authors.forename: K C
authors.initials: KC
authors.lastname: Gallert
authors.forename: G
authors.initials: G
authors.lastname: Krauss
authors.forename: P
authors.initials: P
authors.lastname: Rösch
mesh_terms: D000265:Adenylosuccinate Synthase / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites; D003198:Computer Simulation; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000265:Adenylosuccinate Synthase