title: Homology modelling and active-site-mutagenesis study of the catalytic domain of the pneumococcal phosphorylcholine esterase.
abstract: Streptococcus pneumoniae is among the major human pathogens. Several interactions of this bacterium with its host appear to have been mediated by bacterial cell wall components. Specifically, phosphorylcholine residues covalently attached to teichoic and lipoteichoic acids serve as anchors for many surface-located proteins (choline-binding proteins CBPs), including cell-adhesion and virulence factors, and are also recognized by host response components through choline-binding receptors. In this study, we have performed modelling of the catalytic domain of pneumococcal phosphorylcholine esterase (Pce), a modular enzyme that is capable of removing phosphorycholine residues from teichoic and lipoteichoic acids, remodelling their distribution on the bacterial envelope. We wish to contribute to the structural knowledge of Pce. In this pursuit, 3D models of Pce have been established by homology modelling, using the X-ray structure of enzymes from the alpha/beta metallo-lactamase family fold as templates. Theoretical models of pneumococcal phosphorylcholine esterase (Pce) catalytic modules obtained by homology modelling, and corresponding docking studies employed to find out the residues involved in the binding of Zn ions, are discussed according to mutational studies and ab initio calculations. The presence of a binuclear Zn cluster in the catalytic domain of Pce and a likely coordination model are proposed.
authors.affiliation: Instituto de Química Médica (CSIC), Juan de la Cierva, Madrid, Spain. nuria@suricata.igm.csic.es
authors.forename: Nuria Eugenia
authors.initials: NE
authors.lastname: Campillo
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Páez
authors.forename: Laura
authors.initials: L
authors.lastname: Lagartera
authors.forename: Ana
authors.initials: A
authors.lastname: Gonzalez
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D002412:Cations / Q000737:chemistry; D019295:Computational Biology; D008345:Manganese / Q000737:chemistry / Q000494:pharmacology; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics*; D016415:Sequence Alignment; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D002412:Cations; D008345:Manganese; D002265:Carboxylic Ester Hydrolases