%0 Journal Article %A Morton, Daniel J. %A Williams, Paul %T Characterization of the Outer-membrane Proteins of Haemophilus parainfluenzae Expressed under Iron-sufficient and Iron-restricted Conditions %D 1989 %J Microbiology, %V 135 %N 2 %P 445-451 %@ 1465-2080 %R https://doi.org/10.1099/00221287-135-2-445 %I Microbiology Society, %X 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. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-135-2-445