An oxygen-induced but protein F-independent fibronectin-binding pathway in Streptococcus pyogenes.
Protein F is an important fibronectin-binding adhesin of Streptococcus pyogenes (group A streptococcus). However, all previous analyses of protein F have been conducted in a mutant strain which expresses protein F under anaerobic conditions nonpermissive for expression in other strains. In this study, we have examined the fibronectin-binding properties of several protein F-deficient mutants cultured under aerobic conditions and have identified a second pathway for binding fibronectin. Unlike the case with protein F, exposure to an aerobic environment does not induce transcription of a new gene product. Rather, O2 is apparently required for the modification of a protease-resistant cell surface component into a binding-component form. Modification occurred preferentially at a pH of 6.0 or less, and the binding of the modified component to fibronectin required Zn2+. The oxidizing agent Fe(CN)6 could be substituted for O2 and stimulated expression of binding activity under O2-limiting conditions. Streptococcal fibronectin binding mediated by this pathway but not by protein F could be inhibited by laminin and by streptococcal lipoteichoic acid, a molecule previously implicated as the streptococcal adhesin for fibronectin. The non-protein F-binding activity could also substantially enhance the binding of the organism for fibronectin. The non-protein F-binding activity could also substantially enhance the binding of the organism to basement membrane. By using differential inhibition, analyses of binding to non-protein F mutant strains demonstrated that the total level of fibronectin bound under aerobic conditions reflects contributions from both pathways. Because of its dependence on Zn2+, an oxidant, and pH, this binding activity has been designated the ZOP binding pathway.
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
J Y
JY
Lee
M
M
Caparon
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004492:Edetic Acid / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007797:Laminin / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology*; D014176:Protein Biosynthesis; D013297:Streptococcus pyogenes / Q000378:metabolism*; D013682:Teichoic Acids / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005353:Fibronectins; D007797:Laminin; D008070:Lipopolysaccharides; D013682:Teichoic Acids; C078635:fibronectin-binding proteins, bacterial; C009900:lipoteichoic acid; D004492:Edetic Acid; D015032:Zinc; D010100:Oxygen