title: Characterization of the outer-membrane proteins of Haemophilus parainfluenzae expressed under iron-sufficient and iron-restricted conditions.
abstract: SDS-PAGE of the outer-membrane (OM) proteins of Haemophilus parainfluenzae P205 grown under iron-sufficient conditions revealed three major proteins of 40, 37 and 13 kDa. In addition, growth under conditions of iron-restriction resulted in the expression of at least four iron-repressible OM proteins (IROMPs) of 72, 81, 88 and 90 kDa. OM proteins of 40 and 13 kDa were non-covalently associated with peptidoglycan and were resistant to digestion with trypsin. A 38 kDa peptidoglycan-associated protein, which was masked by the abundant 37 kDa protein, was also observed following tryptic digestion of whole cells or OMs. Neither the 37 kDa protein (which was heat-modifiable) nor the IROMPs were peptidoglycan-associated, and both were cleaved following treatment of whole cells with trypsin, indicating that they are exposed at the cell surface. A variety of IROMPs from five other H. parainfluenzae strains was also observed. In each strain, both the IROMPs and a major protein of 37 kDa were exposed at the cell surface.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nottingham, University Park, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Morton
authors.forename: P
authors.initials: P
authors.lastname: Williams
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis*; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D006193:Haemophilus influenzae / Q000378:metabolism*; D006358:Hot Temperature; D007501:Iron; D008970:Molecular Weight; D010457:Peptidoglycan / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D010457:Peptidoglycan; D007501:Iron; D014357:Trypsin