title: Enterococcus faecalis senses target cells and in response expresses cytolysin.
abstract: Many virulent strains of Enterococcus faecalis produce a two-subunit toxin, termed cytolysin. Cytolysin expression is regulated by one of the subunits (CylL(S)'') through a quorum-sensing autoinduction mechanism. We found that when target cells are absent, the other subunit (CylL(L)'') forms a complex with CylL(S)'', blocking it from autoinducing the operon. When target cells are present, however, CylL(L)'' binds preferentially to the target, allowing free CylL(S)'' to accumulate above the induction threshold. Thus, enterococci use CylL(L)'' to actively probe the environment for target cells, and when target cells are detected, allows the organism to express high levels of cytolysin in response.
authors.affiliation: Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Stanton L. Young Biomedical Research Center, Room 356, Post Office Box 26901, Oklahoma City, OK 73190, USA.
authors.forename: Phillip S
authors.initials: PS
authors.lastname: Coburn
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Pillar
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Jett
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Haas
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gilmore
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001430:Bacteriocins; D013293:Enterococcus faecalis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006461:Hemolysis; D006801:Humans; D008051:Lipid Bilayers / Q000378:metabolism; D008954:Models, Biological; D009876:Operon; D021122:Protein Subunits / Q000378:metabolism; D020349:Surface Plasmon Resonance; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; D008051:Lipid Bilayers; D021122:Protein Subunits; D037521:Virulence Factors; C120351:cytolysin, Enterococcus faecalis