可变的DNA识别位点组织建立了利福平介导的肠球菌对达托霉素的细胞壁应激反应。
A variable DNA recognition site organization establishes the LiaR-mediated cell envelope stress response of enterococci to daptomycin.
作者信息
Davlieva Milya, Shi Yiwen, Leonard Paul G, Johnson Troy A, Zianni Michael R, Arias Cesar A, Ladbury John E, Shamoo Yousif
机构信息
Department of BioSciences, Rice University, Houston, TX 77005, USA.
Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA Center for Biomolecular Structure and Function, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
出版信息
Nucleic Acids Res. 2015 May 19;43(9):4758-73. doi: 10.1093/nar/gkv321. Epub 2015 Apr 19.
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. LiaR(D191N) 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. 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.
LiaR是肠球菌及许多其他革兰氏阳性菌中细胞包膜应激反应的“主调控因子”。liaR的突变可导致对包括环脂肽达托霉素在内的多种抗生素产生耐药性。LiaR会因膜应激而发生磷酸化,从而调节下游靶标操纵子。通过对liaXYZ和liaFSR操纵子上游区域进行DNA足迹分析,我们发现LiaR结合的一段DNA延伸超出了推测的典型共有序列,这表明对靶标操纵子的调控更为复杂。我们接着确定了最初从病原菌粪肠球菌S613中鉴定出的LiaR适应性突变(D191N)导致对达托霉素耐药性增加的生化和结构基础。LiaR(D191N)增加了LiaR的寡聚化,形成一种组成型激活的四聚体,即使在没有磷酸化的情况下也对DNA具有高亲和力,从而导致耐药性增加。与推测的共有序列以及相邻二级序列复合的LiaR DNA结合结构域的晶体结构表明,结合后,LiaR会诱导DNA弯曲,这与RNA聚合酶向转录起始位点的募集增加以及靶标操纵子的上调一致。
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