Growth Phase-Dependent Modulation of Rgg Binding Specificity in Streptococcus pyogenes
Growth Phase-Dependent Modulation of Rgg Binding Specificity in Streptococcus pyogenes
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DOI：
10.1128/jb.06709-11
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发表时间：
2012-08-01
影响因子：
3.2
通讯作者：
Chaussee, Michael S.
中科院分区：
文献类型：
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作者：
Anbalagan, Srivishnupriya;Dmitriev, Alexander;Chaussee, Michael S.
链球菌为链球菌RGG是一种转录调节剂，它与辅因子LACD.1相互作用，以控制包括SPEB在内的基因的生长阶段依赖性表达，它编码了分泌的半胱氨酸蛋白酶。当糖酵解中间体丰富的方式以防止RGG介导的SPEB表达通过与启动子区域的结合来阻止SPEB表达激活的方式，LACD.1被认为与RGG相互作用。当中间体减小时，LACD.1从RGG分离并与SPEB启动子结合以激活表达。这项研究的目的是确定在生长的指数阶段，RGG是否与染色质结合，并确定鉴定结合位点。通过染色质免疫沉淀与DNA微阵列确定的RGG结合到62个染色体位点。 38位在非编码DNA中，包括编码M蛋白（M49）基因上游的位点（M49），血清不透明度因子（SOF），纤连蛋白质结合蛋白（SFBX49）和预言的已编码的超级抗体，SPEH。这些位点中的每一个都包含一个由RGG调节的启动子，该启动子由转录融合测定确定。纯化的RGG还与EMM49，SOF和SFBX49的启动子区域结合。用LACD.1突变体获得的结果表明，lacd.1和RGG对于抑制EMM49，SOF，SFBX49和SPEH表达都是必需的。总体而言，结果表明，RGG的DNA结合特异性对LACD的环境变化有反应。1依赖性方式，RGG和LACD.1在生长的指数阶段直接控制毒力基因表达。
Streptococcus pyogenes Rgg is a transcriptional regulator that interacts with the cofactor LacD.1 to control growth phase-dependent expression of genes, including speB, which encodes a secreted cysteine protease. LacD.1 is thought to interact with Rgg when glycolytic intermediates are abundant in a manner that prevents Rgg-mediated activation of speB expression via binding to the promoter region. When the intermediates diminish, LacD.1 dissociates from Rgg and binds to the speB promoter to activate expression. The purpose of this study was to determine if Rgg bound to chromatin during the exponential phase of growth and, if so, to identify the binding sites. Rgg bound to 62 chromosomal sites, as determined by chromatin immunoprecipitation coupled with DNA microarrays. Thirty-eight were within noncoding DNA, including sites upstream of the genes encoding the M protein (M49), serum opacity factor (SOF), fibronectin-binding protein (SfbX49), and a prophage-encoded superantigen, SpeH. Each of these sites contained a promoter that was regulated by Rgg, as determined with transcriptional fusion assays. Purified Rgg also bound to the promoter regions of emm49, sof, and sfbX49 in vitro. Results obtained with a lacD.1 mutant showed that both LacD.1 and Rgg were necessary for the repression of emm49, sof, sfbX49, and speH expression. Overall, the results indicated that the DNA binding specificity of Rgg is responsive to environmental changes in a LacD.1-dependent manner and that Rgg and LacD.1 directly control virulence gene expression in the exponential phase of growth.