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Title: A variable DNA recognition site organization establishes the LiaR-mediated cell envelope stress response of enterococci to daptomycin

LiaR is a ‘master regulator’ of the cell envelope stress response in enterococci and many other Gram-positive organisms. Mutations to liaR can lead to antibiotic resistance to a variety of antibiotics including the cyclic lipopeptide daptomycin. LiaR is phosphorylated in response to membrane stress to regulate downstream target operons. Using DNA footprinting of the regions upstream of the liaXYZ and liaFSR operons we show that LiaR binds an extended stretch of DNA that extends beyond the proposed canonical consensus sequence suggesting a more complex level of regulatory control of target operons. We go on to determine the biochemical and structural basis for increased resistance to daptomycin by the adaptive mutation to LiaR (D191N) first identified from the pathogen Enterococcus faecalis S613. LiaRD191N increases oligomerization of LiaR to form a constitutively activated tetramer that has high affinity for DNA even in the absence of phosphorylation leading to increased resistance. The crystal structures of the LiaR DNA binding domain complexed to the putative consensus sequence as well as an adjoining secondary sequence show that upon binding, LiaR induces DNA bending that is consistent with increased recruitment of RNA polymerase to the transcription start site and upregulation of target operons.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [2] ;  [1]
  1. Rice Univ., Houston, TX (United States)
  2. The Univ. of Texas MD Anderson Cancer Center, Houston, TX (United States)
  3. The Ohio State Univ., Columbus, OH (United States)
  4. Univ. of Texas Medical School at Houston, Houston, TX (United States); The Univ. of Texas Health Science Center at Houston, Houston, TX (United States); Univ. El Bosque, Bogota (Columbia)
Publication Date:
OSTI Identifier:
1223722
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nucleic Acids Research
Additional Journal Information:
Journal Volume: 43; Journal Issue: 9; Journal ID: ISSN 0305-1048
Publisher:
Oxford University Press
Research Org:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES