Human salivary proteins with affinity to lipoteichoic acid of Enterococcus faecalis

• Published in: Molecular immunology 2016-09, Vol.77, p.52-59
• Main Authors: Baik, Jung Eun, Choe, Hyuk-Il, Hong, Sun Woong, Kang, Seok-Seong, Ahn, Ki Bum, Cho, Kun, Yun, Cheol-Heui, Han, Seung Hyun
• Format: Article
• Language: English
• Subjects: Enterococcus faecalis; Enterococcus faecalis - immunology; Enterococcus faecalis - metabolism; Enterococcus faecalis - pathogenicity; Humans; Innate immunity; Lipopolysaccharides - immunology; Lipopolysaccharides - metabolism; Lipoteichoic acid; Saliva; Saliva - chemistry; Saliva - immunology; Saliva - metabolism; Salivary Proteins and Peptides - chemistry; Salivary Proteins and Peptides - immunology; Salivary Proteins and Peptides - metabolism; Spectroscopy, Fourier Transform Infrared; Teichoic Acids - immunology; Teichoic Acids - metabolism; Virulence Factors - immunology; Virulence Factors - metabolism
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/j.molimm.2016.07.013

•E. faecalis LTA-binding proteins were isolated in the human saliva with biotinylated LTA and avidin-beads.•The proteins were identified with a high-resolution LTQ-Orbitrap hybrid Fourier transform mass spectrometry.•Interaction between E. faecalis LTA and a binding protein lipocalin-1 was confirmed through a pull-down assay.•Hemoglobin inhibited the biofilm formation of E. faecalis whereas lipocalin-1 did not show such effect.•E. faecalis LTA-binding proteins are not always responsible for the bacterial pathogenesis. Enterococcus faecalis is associated with refractory apical periodontitis and its lipoteichoic acid (Ef.LTA) is considered as a major virulence factor. Although the binding proteins of Ef.LTA may play an important role for mediating infection and immunity in the oral cavity, little is known about Ef.LTA-binding proteins (Ef.LTA-BPs) in saliva. In this study, we identified salivary Ef.LTA-BPs with biotinylated Ef.LTA (Ef.LTA-biotin) through mass spectrometry. The biotinylation of Ef.LTA was confirmed by binding capacity with streptavidin-FITC on CHO/CD14/TLR2 cells. The biological activity of Ef.LTA-biotin was determined based on the induction of nitric oxide and macrophage inflammatory protein-1α in a macrophage cell-line, RAW 264.7. To identify salivary Ef.LTA-BPs, the Ef.LTA-biotin was mixed with a pool of human saliva obtained from nine healthy subjects followed by precipitation with a streptavidin-coated bead. Ef.LTA-BPs were then separated with 12% SDS-PAGE and subjected to the mass spectrometry. Six human salivary Ef.LTA-BPs including short palate lung and nasal epithelium carcinoma-associated protein 2, zymogen granule protein 16 homolog B, hemoglobin subunit α and β, apolipoprotein A-I, and lipocalin-1 were identified with statistical significance (P