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Structure and DNA-binding properties of the cytolysin regulator CylR2 from Enterococcus faecalis.

Authors
  • Rumpel, Sigrun
  • Razeto, Adelia
  • Pillar, Chris M
  • Vijayan, Vinesh
  • Taylor, Austin
  • Giller, Karin
  • Gilmore, Michael S
  • Becker, Stefan
  • Zweckstetter, Markus
Type
Published Article
Journal
The EMBO journal
Publication Date
Sep 15, 2004
Volume
23
Issue
18
Pages
3632–3642
Identifiers
PMID: 15359276
Source
Medline
License
Unknown

Abstract

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 beta-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.

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