Okada N, Geist R T, Caparon M G
Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110-1093.
Mol Microbiol. 1993 Mar;7(6):893-903. doi: 10.1111/j.1365-2958.1993.tb01180.x.
Transcription of the antiphagocytic M protein in the group A streptococcus (Streptococcus pyogenes) is environmentally regulated in response to CO2 and requires Mry, a trans-acting positive regulatory protein. We have examined the role of Mry in environmental regulation by analysing the factors that regulate expression of the gene that encodes Mry (mry). By employing a strategy that utilizes integrational plasmids, it was found that expression of mry requires the participation of DNA sequences that extend 473 base pairs upstream of the Mry coding region. Transcription of mry, as analysed in S1 nuclease protection assays, is initiated from two separate promoters located within this extended regulatory region. Construction and analysis of transcriptional fusions between the mry promoters and a promoterless chloramphenicol acetyltransferase gene demonstrated that mry is autoregulated and environmentally regulated in response to the level of CO2. These data suggest a model for the regulation of virulence in S. pyogenes where positive transcriptional control of mry in response to environmental stimuli regulates the expression of the M protein.
A群链球菌（化脓性链球菌）中抗吞噬M蛋白的转录受环境调控，对二氧化碳作出响应，并且需要反式作用阳性调节蛋白Mry。我们通过分析调节编码Mry的基因（mry）表达的因素，研究了Mry在环境调控中的作用。通过采用利用整合质粒的策略，发现mry的表达需要Mry编码区上游延伸473个碱基对的DNA序列的参与。如在S1核酸酶保护试验中分析的那样，mry的转录起始于位于这个延伸调控区内的两个独立启动子。mry启动子与无启动子氯霉素乙酰转移酶基因之间转录融合体的构建和分析表明，mry是自我调节的，并且对二氧化碳水平作出环境调控响应。这些数据提示了一个化脓性链球菌毒力调控模型，其中mry对环境刺激的阳性转录控制调节M蛋白的表达。
