Shi Ke, Brown C Kent, Gu Zu-Yi, Kozlowicz Briana K, Dunny Gary M, Ohlendorf Douglas H, Earhart Cathleen A
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
Proc Natl Acad Sci U S A. 2005 Dec 20;102(51):18596-601. doi: 10.1073/pnas.0506163102. Epub 2005 Dec 8.
Many bacterial activities, including expression of virulence factors, horizontal genetic transfer, and production of antibiotics, are controlled by intercellular signaling using small molecules. To date, understanding of the molecular mechanisms of peptide-mediated cell-cell signaling has been limited by a dearth of published information about the molecular structures of the signaling components. Here, we present the molecular structure of PrgX, a DNA- and peptide-binding protein that regulates expression of the conjugative transfer genes of the Enterococcus faecalis plasmid pCF10 in response to an intercellular peptide pheromone signal. Comparison of the structures of PrgX and the PrgX/pheromone complex suggests that pheromone binding destabilizes PrgX tetramers, opening a 70-bp pCF10 DNA loop required for conjugation repression.
许多细菌活动，包括毒力因子的表达、水平基因转移和抗生素的产生，都通过小分子进行细胞间信号传导来控制。迄今为止，由于关于信号传导成分分子结构的已发表信息匮乏，对肽介导的细胞间信号传导分子机制的了解一直有限。在此，我们展示了PrgX的分子结构，PrgX是一种DNA和肽结合蛋白，它响应细胞间肽信息素信号调节粪肠球菌质粒pCF10接合转移基因的表达。PrgX与PrgX/信息素复合物结构的比较表明，信息素结合会使PrgX四聚体不稳定，打开接合抑制所需的70 bp pCF10 DNA环。
