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Structure and DNA‐binding properties of the cytolysin regulator CylR2 from Enterococcus faecalis
Author(s) -
Rumpel Sigrun,
Razeto Adelia,
Pillar Chris M,
Vijayan Vinesh,
Taylor Austin,
Giller Karin,
Gilmore Michael S,
Becker Stefan,
Zweckstetter Markus
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600367
Subject(s) - enterococcus faecalis , library science , physics , biology , chemistry , genetics , computer science , bacteria , staphylococcus aureus
Enterococcus faecalis is one of the major causes for hospital‐acquired antibiotic‐resistant infections. It produces an exotoxin, called cytolysin, which is lethal for a wide range of Gram‐positive bacteria and is toxic to higher organisms. Recently, the regulation of the cytolysin operon was connected to autoinduction by a quorum‐sensing mechanism involving the CylR1/CylR2 two‐component regulatory system. We report here the crystal structure of CylR2 and its properties in solution as determined by heteronuclear NMR spectroscopy. The structure reveals a rigid dimer containing a helix–turn–helix DNA‐binding motif as part of a five‐helix bundle that is extended by an antiparallel β‐sheet. We show that CylR2 is a DNA‐binding protein that binds specifically to a 22 bp fragment of the cytolysin promoter region. NMR chemical shift perturbation experiments identify surfaces involved in DNA binding and are in agreement with a model for the CylR2/DNA complex that attributes binding specificity to a complex network of CylR2/DNA interactions. Our results propose a mechanism where repression is achieved by CylR2 obstruction of the promoter preventing biosynthesis of the cytolysin operon transcript.