title: A deeper analysis of the epitope/paratope of PLY-5, a mouse monoclonal antibody which recognises the conserved undecapeptide tryptophan-rich loop (ECTGLAWEWWR) of bacterial cholesterol-dependent cytolysins.
abstract: A previous study showed that the minimal epitope recognised by the PLY-5 mAb in the conserved undecapeptide Trp-rich loop of bacterial CDCs should consist of WEWWRT (Jacobs et al., 1999) [5]. Now, through immunoscreening of amino acid substitution analogues, it is concluded that the second Trp and the Arg residues are essential in the PLY-5 epitope. The E residue is an auxiliary epitope contributor. Antibody modelling and docking simulations provided support for these findings. For recognition by the antibody, the Trp-rich loop flipped out, mimicking the mechanism of membrane insertion. The displaced second Trp was seen to establish aromatic stacking interactions with aromatic residues of the antibody paratope and the notably extruded guanidium tip of the arginine residue mediated electrostatic interactions with well-exposed carboxylic groups of glutamic residues on the surface of the paratope. Thus, the epitope/paratope interaction is mainly mediated by aromatic and by ionic interactions.
authors.affiliation: Immunology Area, School of Medicine and Health Sciences, Oviedo University, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: González-Menéndez
authors.forename: Marcos
authors.initials: M
authors.lastname: García-Ocaña
authors.forename: Juan R
authors.initials: JR
authors.lastname: de los Toyos
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D019138:Antibodies, Blocking / Q000235:genetics / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000276:immunology; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000276:immunology; D002784:Cholesterol / Q000276:immunology*; D017124:Conserved Sequence; D003603:Cytotoxins / Q000037:antagonists & inhibitors / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006460:Hemolysin Proteins / Q000037:antagonists & inhibitors / Q000276:immunology; D006461:Hemolysis / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000276:immunology; D013301:Streptolysins / Q000037:antagonists & inhibitors / Q000276:immunology*; D014364:Tryptophan / Q000276:immunology
chemical_list: D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D000939:Epitopes; D006460:Hemolysin Proteins; D009842:Oligopeptides; C108448:Pyolysin, Arcanobacterium pyogenes; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; C542392:vaginolysin, Gardnerella vaginalis; D014364:Tryptophan; D002784:Cholesterol