title: Antigenic sites on porin of Haemophilus influenzae type b: mapping with synthetic peptides and evaluation of structure predictions.
abstract: The major surface-located protein in the outer membrane of Haemophilus influenzae type b (Hib) is porin, molecular mass, 38 kDa, 341 amino acids. To define precisely the molecular reactivities of nine mouse monoclonal antibodies (MAbs) against Hib porin, overlapping hexapeptides corresponding to the entire sequence of porin were synthesized. The epitopes recognized by the MAbs were mapped by enzyme-linked immunosorbent assay to stretches of 6 to 11 amino acids. Antigenic sites between amino acids 112 and 126, 148 and 153, 162 and 172, and 318 and 325 were identified. The antigenic sites between amino acids 162 and 172 and between amino acids 318 and 325 were determined by flow cytometry to be on the bacterial cell surface. Four MAbs, POR.2, POR.3, POR.4, and POR.5, that react with amino acids 162 to 172 were able to discriminate among porins from the three major outer membrane protein subtypes of Hib, i.e., 1H, 2L, and 6U. A model for the topological organization of Hib porin was created by calculating the hydrophobicity, amphiphilicity, and turn propensity in its amino acid sequence. Determination of the molecular reactivities of the anti-Hib porin MAbs provided substantive evidence for the orientation of selected regions of porin in the outer membrane of Hib.
authors.affiliation: Department of Microbiology and Immunology, McGill University, Montreal, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Srikumar
authors.forename: D
authors.initials: D
authors.lastname: Dahan
authors.forename: M F
authors.initials: MF
authors.lastname: Gras
authors.forename: M J
authors.initials: MJ
authors.lastname: Ratcliffe
authors.forename: L
authors.initials: L
authors.lastname: van Alphen
authors.forename: J W
authors.initials: JW
authors.lastname: Coulton
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005434:Flow Cytometry; D006193:Haemophilus influenzae / Q000276:immunology*; D007473:Ion Channels / Q000276:immunology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology*; D010449:Peptide Mapping; D018272:Porins; D011487:Protein Conformation
chemical_list: D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D000939:Epitopes; D007473:Ion Channels; D010446:Peptide Fragments; D018272:Porins