title: Silkworm apolipophorin protein inhibits hemolysin gene expression of Staphylococcus aureus via binding to cell surface lipoteichoic acids.
abstract: We previously reported that a silkworm hemolymph protein, apolipophorin (ApoLp), binds to the cell surface of Staphylococcus aureus and inhibits expression of the saePQRS operon encoding a two-component system, SaeRS, and hemolysin genes. In this study, we investigated the inhibitory mechanism of ApoLp on S. aureus hemolysin gene expression. ApoLp bound to lipoteichoic acids (LTA), an S. aureus cell surface component. The addition of purified LTA to liquid medium abolished the inhibitory effect of ApoLp against S. aureus hemolysin production. In an S. aureus knockdown mutant of ltaS encoding LTA synthetase, the inhibitory effects of ApoLp on saeQ expression and hemolysin production were attenuated. Furthermore, the addition of anti-LTA monoclonal antibody to liquid medium decreased the expression of S. aureus saeQ and hemolysin genes. In S. aureus strains expressing SaeS mutant proteins with a shortened extracellular domain, ApoLp did not decrease saeQ expression. These findings suggest that ApoLp binds to LTA on the S. aureus cell surface and inhibits S. aureus hemolysin gene expression via a two-component regulatory system, SaeRS.
authors.affiliation: From the Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Omae
authors.affiliation: From the Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hanada
authors.affiliation: From the Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Sekimizu
authors.affiliation: From the Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: kaito@mol.f.u-tokyo.ac.jp.
authors.forename: Chikara
authors.initials: C
authors.lastname: Kaito
mesh_terms: D000818:Animals; D001053:Apolipoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D012831:Bombyx / Q000737:chemistry*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D006460:Hemolysin Proteins / Q000096:biosynthesis*; D019476:Insect Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000096:biosynthesis / Q000235:genetics; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism*; D013682:Teichoic Acids / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors
chemical_list: D001053:Apolipoproteins; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D008070:Lipopolysaccharides; C433805:SaeR protein, Staphylococcus aureus; D013682:Teichoic Acids; D014157:Transcription Factors; C009900:lipoteichoic acid; D011494:Protein Kinases; C527351:SaeS protein, Staphylococcus aureus
keywords: Bacterial Protein Kinases; Bacterial Signal Transduction; Lipoprotein; Lipoprotein Receptor; Receptors; Silkworm; Staphylococcus aureus; Transcription Regulation