title: The identification and functional characterization of WxL proteins from Enterococcus faecium reveal surface proteins involved in extracellular matrix interactions.
abstract: The WxL domain recently has been identified as a novel cell wall binding domain found in numerous predicted proteins within multiple Gram-positive bacterial species. However, little is known about the function of proteins containing this novel domain. Here, we identify and characterize 6 Enterococcus faecium proteins containing the WxL domain which, by reverse transcription-PCR (RT-PCR) and genomic analyses, are located in three similarly organized operons, deemed WxL loci A, B, and C. Western blotting, electron microscopy, and enzyme-linked immunosorbent assays (ELISAs) determined that genes of WxL loci A and C encode antigenic, cell surface proteins exposed at higher levels in clinical isolates than in commensal isolates. Secondary structural analyses of locus A recombinant WxL domain-containing proteins found they are rich in β-sheet structure and disordered segments. Using Biacore analyses, we discovered that recombinant WxL proteins from locus A bind human extracellular matrix proteins, specifically type I collagen and fibronectin. Proteins encoded by locus A also were found to bind to each other, suggesting a novel cell surface complex. Furthermore, bile salt survival assays and animal models using a mutant from which all three WxL loci were deleted revealed the involvement of WxL operons in bile salt stress and endocarditis pathogenesis. In summary, these studies extend our understanding of proteins containing the WxL domain and their potential impact on colonization and virulence in E. faecium and possibly other Gram-positive bacterial species.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas, USA Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center, Houston, Texas, USA.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Galloway-Peña
authors.affiliation: Center for Infectious and Inflammatory Diseases, Institute for Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Liang
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center, Houston, Texas, USA.
authors.forename: Kavindra V
authors.initials: KV
authors.lastname: Singh
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas, USA Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center, Houston, Texas, USA.
authors.forename: Puja
authors.initials: P
authors.lastname: Yadav
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas, USA.
authors.forename: Chungyu
authors.initials: C
authors.lastname: Chang
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Laboratory of Microbial Gene Technology and Food Microbiology, The Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Sabina Leanti
authors.initials: SL
authors.lastname: La Rosa
authors.affiliation: Department of Infectious Diseases, Infection Control and Employee Health, M. D. Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Samuel
authors.initials: S
authors.lastname: Shelburne
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas, USA.
authors.forename: Hung
authors.initials: H
authors.lastname: Ton-That
authors.affiliation: Center for Infectious and Inflammatory Diseases, Institute for Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA.
authors.forename: Magnus
authors.initials: M
authors.lastname: Höök
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas, USA Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center, Houston, Texas, USA Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center, Houston, Texas, USA Barbara.E.Murray@uth.tmc.edu.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Murray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016984:Enterococcus faecium / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D005109:Extracellular Matrix / Q000378:metabolism*; D016908:Gram-Positive Bacterial Infections / Q000378:metabolism* / Q000382:microbiology; D006801:Humans; D008969:Molecular Sequence Data; D009876:Operon; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D001426:Bacterial Proteins