title: Active-site mobility revealed by the crystal structure of arylmalonate decarboxylase from Bordetella bronchiseptica.
abstract: Arylmalonate decarboxylase (AMDase) from Bordetella bronchiseptica catalyzes the enantioselective decarboxylation of arylmethylmalonates without the need for an organic cofactor or metal ion. The decarboxylation reaction is of interest for the synthesis of fine chemicals. As basis for an analysis of the catalytic mechanism of AMDase and for a rational enzyme design, we determined the X-ray structure of the enzyme up to 1.9 A resolution. Like the distantly related aspartate or glutamate racemases, AMDase has an aspartate transcarbamoylase fold consisting of two alpha/beta domains related by a pseudo dyad. However, the domain orientation of AMDase differs by about 30 degrees from that of the glutamate racemases, and also significant differences in active-site structures are observed. In the crystals, four independent subunits showing different conformations of active-site loops are present. This finding is likely to reflect the active-site mobility necessary for catalytic activity.
authors.affiliation: Center for Biotechnology and Biomedicine, Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany.
authors.forename: E Bartholomeus
authors.initials: EB
authors.lastname: Kuettner
authors.forename: Antje
authors.initials: A
authors.lastname: Keim
authors.forename: Markus
authors.initials: M
authors.lastname: Kircher
authors.forename: Susann
authors.initials: S
authors.lastname: Rosmus
authors.forename: Norbert
authors.initials: N
authors.lastname: Sträter
mesh_terms: D001665:Binding Sites; D016950:Bordetella bronchiseptica / Q000201:enzymology* / Q000235:genetics; D002262:Carboxy-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D013379:Substrate Specificity
chemical_list: D004220:Disulfides; D018698:Glutamic Acid; D002262:Carboxy-Lyases; C071852:malonate decarboxylase