A Novel secreted endoglycosidase from Enterococcus faecalis with activity on human immunoglobulin G and ribonuclease B

Research output: Contribution to journalArticle

Abstract

The human pathogen Enterococcus faecalis can degrade the N-linked glycans of human RNase B to acquire nutrients, but no gene or protein has been associated with this activity. We identified an 88-kDa secreted protein, endoglycosidase (Endo) E, which is most likely responsible for this activity. EndoE, encoded by ndoE, consists of an α-domain with a family 18 glycosyl hydrolase motif and a β-domain similar to family 20 glycosyl hydrolases. Phylogenetic analysis of EndoE indicates that the α-domain is related to human chitobiases, and the β-domain is related to bacterial and human hexosaminidases. Recombinant expression of full-length EndoE or EndoEα, site-directed mutagenesis of the catalytic residues, mass spectroscopy, and homology modeling shows that EndoEα hydrolyzes the glycan on human RNase B, whereas EndoEβ hydrolyzes the conserved glycan on IgG. Denaturation experiments indicate that the chitinase activity on RNase B is not dependent on the tertiary structure, although it is on IgG. The ndoE gene and secreted EndoE are present in most E. faecalis but not in Enterococcus faecium isolates. Correspondingly, E. faecalis, but not E. faecium, degrades the glycan on RNase B during growth. Thus, we have identified a secreted enzyme from E. faecalis, EndoE, which by two distinct activities hydrolyzes the glycans on RNase B and IgG. Both activities could be important for the molecular pathogenesis and persistence of E. faecalis during human infections.

Details

Authors
External organisations
  • Rockefeller University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medicinal Chemistry
  • Microbiology in the medical area
Original languageEnglish
Pages (from-to)22558-22570
Number of pages13
JournalJournal of Biological Chemistry
Volume279
Issue number21
Publication statusPublished - 2004 May 21
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes