The identification and functional characterization of WxL proteins from Enterococcus faecium reveal surface proteins involved in extracellular matrix interactions

Jessica R. Galloway-Peña, Xiaowen Liang, Kavindra V. Singh, Puja Yadav, Chungyu Chang, Sabina Leanti La Rosa, Samuel Shelburne, Hung Ton-That, Magnus Höök, Barbara E. Murray

Research output: Contribution to journalArticle

17 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)882-892
Number of pages11
JournalJournal of bacteriology
Volume197
Issue number5
DOIs
StatePublished - 2015

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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