title: Covalently bound substrate at the regulatory site of yeast pyruvate decarboxylases triggers allosteric enzyme activation.
abstract: The mechanism by which the enzyme pyruvate decarboxylase from two yeast species is activated allosterically has been elucidated. A total of seven three-dimensional structures of the enzyme, of enzyme variants, or of enzyme complexes from two yeast species, three of them reported here for the first time, provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal. This reaction causes the shift of a neighboring amino acid, which eventually leads to the rigidification of two otherwise flexible loops, one of which provides two histidine residues necessary to complete the enzymatically competent active site architecture. The structural data are complemented and supported by kinetic investigations and binding studies, providing a consistent picture of the structural changes occurring upon enzyme activation.
authors.affiliation: Institute for Biochemistry and Biotechnology, Faculty of Biological Sciences, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle (Saale), Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Kutter
authors.forename: Manfred S
authors.initials: MS
authors.lastname: Weiss
authors.forename: Georg
authors.initials: G
authors.lastname: Wille
authors.forename: Ralph
authors.initials: R
authors.lastname: Golbik
authors.forename: Michael
authors.initials: M
authors.lastname: Spinka
authors.forename: Stephan
authors.initials: S
authors.lastname: König
mesh_terms: D000494:Allosteric Regulation / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D005656:Fungal Proteins / Q000737:chemistry*; D007700:Kinetics; D007716:Kluyveromyces / Q000201:enzymology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D011767:Pyruvate Decarboxylase / Q000737:chemistry*; D019289:Pyruvic Acid / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D019289:Pyruvic Acid; D011767:Pyruvate Decarboxylase