Fur and iron transport proteins in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius.
The Brazilian purpuric fever (BPF) clone of Haemophilus influenzae biogroup aegyptius causes a fatal septicaemic disease, resembling fulminant meningococcal sepsis, in children. When isolate F3031 was grown under iron-limiting conditions, the presence of several iron-regulated proteins of 38-110 kDa was revealed by electrophoretic analysis and a Fur homologue was shown by immunoblotting. Dot-blot assays and immunoblotting indicated that BPF cells bound human transferrin and contained transferrin-binding proteins in the outer membrane. However, the binding activity and the biosynthesis of these proteins were detected even under iron-rich conditions. Immunoblot analysis demonstrated the presence of a periplasmic protein related to the ferric iron-binding protein A (FbpA), the major iron-binding protein described in Neisseria spp. However, the FbpA homologue in strain F3031 was constitutively expressed and was smaller than the periplasmic protein detected in H. influenzae type b strain Eagan. The periplasm of strain F3031 also contained a protein related to the Streptococcus parasanguis FimA protein which recently has been shown to be involved in iron acquisition in Yersinia pestis. Although the Eagan and F3031 FimA homologues had a similar mol. wt, of 31 kDa, the expression of the BPF fimA-like gene was not regulated by the iron concentration of the culture medium.
L M
LM
Smoot
E C
EC
Bell
Department of Molecular Biology and Immunology, Oregon Health Sciences University, Portland, OR 97201, USA.
J H
JH
Crosa
Department of Microbiology, Miami University, Oxford, OH 45056.
L A
LA
Actis
D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D001426:Bacterial Proteins / Q000502:physiology*; D015153:Blotting, Western; D001938:Brazil; D002352:Carrier Proteins; D002648:Child; D004591:Electrophoresis, Polyacrylamide Gel; D036781:Fimbriae Proteins; D015964:Gene Expression Regulation, Bacterial; D006192:Haemophilus Infections / Q000503:physiopathology*; D006193:Haemophilus influenzae / Q000472:pathogenicity* / Q000502:physiology; D006427:Hemin / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism; D008970:Molecular Weight; D011693:Purpura / Q000382:microbiology*; D012097:Repressor Proteins / Q000502:physiology*; D018805:Sepsis / Q000503:physiopathology; D014168:Transferrin / Q000502:physiology*
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D012097:Repressor Proteins; D014168:Transferrin; C068477:ferric uptake regulating proteins, bacterial; C093280:fibrinogen-binding protein A, Staphylococcus aureus; C063055:fimbrillin; D036781:Fimbriae Proteins; D006427:Hemin; D007501:Iron