Lipopolysaccharides of Actinobacillus pleuropneumoniae bind pig hemoglobin

• Published in: Infection and Immunity 1995-02, Vol.63 (2), p.656-662
• Main Authors: Belanger, M. (Universite de Montreal, Saint-Hyacinthe, Quebec, Canada.), Begin, C, Jacques, M
• Format: Article
• Language: English
• Subjects: ACIDE GRAS; ACIDOS GRASOS; ACTINOBACILLUS PLEUROPNEUMONIAE; Actinobacillus pleuropneumoniae - pathogenicity; Acute-Phase Proteins; Amino Acid Sequence; Animals; Bacterial diseases; Bacterial diseases of the respiratory system; Bacteriology; Biological and medical sciences; Carrier Proteins; CERDO; Chromatography, Affinity; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Fundamental and applied biological sciences. Psychology; HEMOGLOBINA; HEMOGLOBINE; Hemoglobins - metabolism; Human bacterial diseases; In Vitro Techniques; Infectious diseases; Iron - metabolism; Lipid A - metabolism; LIPOPOLISACARIDOS; LIPOPOLYSACCHARIDE; Lipopolysaccharides - metabolism; Medical sciences; Membrane Glycoproteins; Microbiology; Molecular Sequence Data; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Polymyxin B - pharmacology; PORCIN; Protein Binding; Respiratory System - microbiology; Swine
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/iai.63.2.656-662.1995

A previous study indicated that lipopolysaccharides (LPS) extracted from Actinobacillus pleuropneumoniae bind two low-molecular-mass proteins, of approximately 10 and 11 kDa, present in porcine respiratory tract secretions (M. Belanger, D. Dubreuil, and M. Jacques, Infect. Immun. 62:868-873, 1994). In the present study, we determined the N-terminal amino acid sequences of these two proteins, which revealed high homology with the alpha and beta chains of pig hemoglobin. Some isolates of A. pleuropneumoniae were able to use hemoglobin from various animal species as well as other heme compounds as sole sources of iron for growth, while other isolates were unable to use them. Immunoelectron microscopy showed binding of pig hemoglobin at the surface of all A. pleuropneumoniae isolates as well as labeling of outer membrane blebs. We observed, using Western blotting (immunoblotting), that the lipid A-core region of LPS of all isolates was binding pig hemoglobin. Furthermore, lipid A obtained after acid hydrolysis of LPS extracted from A. pleuropneumoniae was able to bind pig hemoglobin and this binding was completely abolished by preincubation of lipid A with polymyxin B but was not inhibited by preincubation with glucosamines. Fatty acids constituting the lipid A of A. pleuropneumoniae, namely, dodecanoic acid, tetradecanoic acid, 3-hydroxytetradecanoic acid, hexadecanoic acid, and octadecanoic acid, were also binding pig hemoglobin. Our results indicate that LPS of all A. pleuropneumoniae isolates tested bind pig hemoglobin and that lipid A is involved in this binding. Our results also indicate that some A. pleuropneumoniae isolates are, in addition, able to use hemoglobin for growth. Binding of hemoglobin to LPS might represent an important means by which A. pleuropneumoniae acquires iron in vivo from hemoglobin released from erythrocytes lysed by the action of its hemolysins