title: Crystal structure at 1.2 A resolution and active site mapping of Escherichia coli peptidyl-tRNA hydrolase.
abstract: Peptidyl-tRNA hydrolase activity from Escherichia coli ensures the recycling of peptidyl-tRNAs produced through abortion of translation. This activity, which is essential for cell viability, is carried out by a monomeric protein of 193 residues. The structure of crystalline peptidyl-tRNA hydrolase could be solved at 1.2 A resolution. It indicates a single alpha/beta globular domain built around a twisted mixed beta-sheet, similar to the central core of an aminopeptidase from Aeromonas proteolytica. This similarity allowed the characterization by site-directed mutagenesis of several residues of the active site of peptidyl-tRNA hydrolase. These residues, strictly conserved among the known peptidyl-tRNA hydrolase sequences, delineate a channel which, in the crystal, is occupied by the C-end of a neighbouring peptidyl-tRNA hydrolase molecule. Hence, several main chain atoms of three residues belonging to one peptidyl-tRNA hydrolase polypeptide establish contacts inside the active site of another peptidyl-tRNA hydrolase molecule. Such an interaction is assumed to represent the formation of a complex between the enzyme and one product of the catalysed reaction.
authors.affiliation: Laboratoire de Biochimie, Unit'e de Recherche Associ'ee No. 1970 du Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France.
authors.forename: E
authors.initials: E
authors.lastname: Schmitt
authors.forename: Y
authors.initials: Y
authors.lastname: Mechulam
authors.forename: M
authors.initials: M
authors.lastname: Fromant
authors.forename: P
authors.initials: P
authors.lastname: Plateau
authors.forename: S
authors.initials: S
authors.lastname: Blanquet
mesh_terms: D000333:Aeromonas / Q000201:enzymology; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D002265:Carboxylic Ester Hydrolases; C019674:aminoacyl-tRNA hydrolase