Toyomane Kochi, Furuta Yoshikazu, Fujikura Daisuke, Higashi Hideaki
Division of Infection and Immunity, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan.
PeerJ. 2019 Apr 12;7:e6718. doi: 10.7717/peerj.6718. eCollection 2019.
The anthrax toxin is a virulence factor produced by the bacterium . Transcription of anthrax toxin genes is controlled by the transcription factor AtxA. Thus, AtxA is thought to be a key factor for the pathogenicity of . Despite its important role in infection, the molecular mechanism by which AtxA controls expression of anthrax toxin remains unclear. This study aimed to characterize the molecular mechanism of AtxA-mediated regulation of protective antigen (PA), a component of anthrax toxin encoded by the gene. First, the interaction between the upstream region of and AtxA was evaluated in vivo by constructing a transcriptional fusion of the upstream region with an auxotrophic marker. The results showed that (i) the upstream region of suppressed transcription of the downstream gene and (ii) AtxA recovered suppressed transcription. Second, in vitro analysis using a gel mobility shift assay was performed to evaluate binding specificity of the AtxA-DNA interaction. The result showed sequence-independent binding of AtxA to DNA. Taken together, our findings suggest that the expression of PA was suppressed by the upstream region of and that an interaction of AtxA and the upstream region releases the suppression.
炭疽毒素是由该细菌产生的一种毒力因子。炭疽毒素基因的转录受转录因子AtxA控制。因此，AtxA被认为是该菌致病性的关键因素。尽管AtxA在感染中起重要作用，但其控制炭疽毒素表达的分子机制仍不清楚。本研究旨在阐明AtxA介导的对保护性抗原（PA）调控的分子机制，PA是由该基因编码的炭疽毒素的一个组分。首先，通过构建上游区域与营养缺陷型标记的转录融合体，在体内评估该基因上游区域与AtxA之间的相互作用。结果表明：（i）该基因的上游区域抑制下游基因的转录；（ii）AtxA恢复被抑制的转录。其次，使用凝胶迁移率变动分析进行体外分析，以评估AtxA与DNA相互作用的结合特异性。结果显示AtxA与DNA的结合不依赖于序列。综上所述，我们的研究结果表明，PA的表达受到该基因上游区域的抑制，AtxA与上游区域的相互作用解除了这种抑制。
