Bacterial surface protein L binds and inactivates neutrophil proteins S100A8/A9.
Finegoldia magna is an anaerobic bacterial species that is part of the normal human flora on all nonsterile body surfaces, but it is also a significant opportunistic pathogen causing a wide range of infections. Some isolates of F. magna that are more frequently associated with clinical infection express protein L, a surface protein containing multiple homologous domains (B1-B5) that bind Igs through interactions with Ig L chains. The present study shows that the N-terminal A domain of protein L binds S100A8/A9, antibacterial proteins present in large amounts in the cytoplasm of neutrophils, but also extracellularly in tissues during inflammation. As a result, protein L-expressing F. magna are protected against killing by S100A8/A9. Igs and S100A8/A9 were found to interact independently with protein L, demonstrating that this bacterial surface protein is capable of manipulating both adaptive and innate immune defense mechanisms.
Akerström
Bo
B
Department of Clinical Sciences, Division of Infection Medicine, Lund University, BMC, B14, Solvegatan 19, Lund SE-22184, Sweden. bo.akerstrom@med.lu.se
Björck
Lars
L
D001422:Bacterial Adhesion / Q000276:immunology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology*; D001433:Bacteriolysis / Q000276:immunology; D001770:Blood Bactericidal Activity / Q000276:immunology; D040501:Calgranulin A / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000502:physiology; D040502:Calgranulin B / Q000378:metabolism* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism* / Q000502:physiology*; D006801:Humans; D018375:Neutrophil Activation / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D010460:Peptococcus / Q000254:growth & development / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000378:metabolism; D013297:Streptococcus pyogenes / Q000276:immunology / Q000378:metabolism
D001426:Bacterial Proteins; D040501:Calgranulin A; D040502:Calgranulin B; D004268:DNA-Binding Proteins; C116593:L-protein, Peptococcus magnus