title: Structure of Escherichia coli aspartate α-decarboxylase Asn72Ala: probing the role of Asn72 in pyruvoyl cofactor formation.
abstract: The crystal structure of the Asn72Ala site-directed mutant of Escherichia coli aspartate α-decarboxylase (ADC) has been determined at 1.7 Å resolution. The refined structure is consistent with the presence of a hydrolysis product serine in the active site in place of the pyruvoyl group required for catalysis, which suggests that the role of Asn72 is to protect the ester formed during ADC activation from hydrolysis. In previously determined structures of activated ADC, including the wild type and other site-directed mutants, the C-terminal region of the protein is disordered, but in the Asn72Ala mutant these residues are ordered owing to an interaction with the active site of the neighbouring symmetry-related multimer.
authors.affiliation: University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England. m.e.webb@leeds.ac.uk
authors.forename: Michael E
authors.initials: ME
authors.lastname: Webb
authors.forename: Carina M C
authors.initials: CM
authors.lastname: Lobley
authors.forename: Fatima
authors.initials: F
authors.lastname: Soliman
authors.forename: Mairi L
authors.initials: ML
authors.lastname: Kilkenny
authors.forename: Alison G
authors.initials: AG
authors.lastname: Smith
authors.forename: Tom L
authors.initials: TL
authors.lastname: Blundell
authors.forename: Chris
authors.initials: C
authors.lastname: Abell
mesh_terms: D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D005968:Glutamate Decarboxylase / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: C019104:aspartate-alpha-decarboxylase; D005968:Glutamate Decarboxylase