Furuta Yoshikazu, Cheng Cheng, Zorigt Tuvshinzaya, Paudel Atmika, Izumi Shun, Tsujinouchi Mai, Shimizu Tomoko, Meijer Wim G, Higashi Hideaki
Division of Infection and Immunity, Research Center for Zoonosis Control, Hokkaido Universitygrid.39158.36, Sapporo, Hokkaido, Japan.
UCD School of Biomolecular and Biomedical Science, University College Dublingrid.7886.1, Dublin, Ireland.
mSystems. 2021 Aug 31;6(4):e0029121. doi: 10.1128/mSystems.00291-21. Epub 2021 Jul 20.
AtxA, the master virulence regulator of Bacillus anthracis, regulates the expression of three toxins and genes for capsule formation that are required for the pathogenicity of B. anthracis. Recent transcriptome analyses showed that AtxA affects a large number of genes on the chromosome and plasmids, suggesting a role as a global regulator. However, information on genes directly regulated by AtxA is scarce. In this work, we conducted genome-wide analyses and cataloged the binding sites of AtxA and transcription start sites on the B. anthracis genome. By integrating these results, we detected eight genes as direct regulons of AtxA. These consisted of five protein-coding genes, including two of the three toxin genes, and three genes encoding the small RNAs XrrA and XrrB and a newly discovered 95-nucleotide small RNA, XrrC. Transcriptomes from single-knockout mutants of these small RNAs revealed changes in the transcription levels of genes related to the aerobic electron transport chain, heme biosynthesis, and amino acid metabolism, suggesting their function for the control of cell physiology. These results reveal the first layer of the gene regulatory network for the pathogenicity of B. anthracis and provide a data set for the further study of the genomics and genetics of B. anthracis. Bacillus anthracis is the Gram-positive bacterial species that causes anthrax. Anthrax is still prevalent in countries mainly in Asia and Africa, where it causes economic damage and remains a public health issue. The mechanism of pathogenicity is mainly explained by the three toxin proteins expressed from the pXO1 plasmid and by proteins involved in capsule formation expressed from the pXO2 plasmid. AtxA is a protein expressed from the pXO1 plasmid that is known to upregulate genes involved in toxin production and capsule formation and is thus considered the master virulence regulator of B. anthracis. Therefore, understanding the detailed mechanism of gene regulation is important for the control of anthrax. The significance of this work lies in the identification of genes that are directly regulated by AtxA via genome-wide analyses. The results reveal the first layer of the gene regulatory network for the pathogenicity of B. anthracis and provide useful resources for a further understanding of B. anthracis.
AtxA是炭疽芽孢杆菌的主要毒力调节因子，它调控三种毒素以及荚膜形成相关基因的表达，这些基因对于炭疽芽孢杆菌的致病性至关重要。近期的转录组分析表明，AtxA会影响染色体和质粒上的大量基因，这表明它具有全局调节因子的作用。然而，关于直接受AtxA调控的基因的信息却很匮乏。在这项研究中，我们进行了全基因组分析，并对炭疽芽孢杆菌基因组上AtxA的结合位点和转录起始位点进行了编目。通过整合这些结果，我们检测到八个基因是AtxA的直接调控子。其中包括五个蛋白质编码基因，其中三个毒素基因中有两个，以及三个编码小RNA XrrA和XrrB的基因，还有一个新发现的95个核苷酸的小RNA XrrC。这些小RNA单敲除突变体的转录组揭示了与有氧电子传递链、血红素生物合成和氨基酸代谢相关基因转录水平的变化，这表明它们在控制细胞生理方面的功能。这些结果揭示了炭疽芽孢杆菌致病性基因调控网络的第一层，并为进一步研究炭疽芽孢杆菌的基因组学和遗传学提供了数据集。炭疽芽孢杆菌是导致炭疽病的革兰氏阳性细菌物种。炭疽病在主要位于亚洲和非洲的国家仍然很普遍，在这些国家它会造成经济损失，并且仍然是一个公共卫生问题。致病性机制主要由pXO1质粒表达的三种毒素蛋白以及pXO2质粒表达的参与荚膜形成的蛋白来解释。AtxA是从pXO1质粒表达的一种蛋白质，已知它会上调参与毒素产生和荚膜形成的基因，因此被认为是炭疽芽孢杆菌的主要毒力调节因子。所以，了解基因调控的详细机制对于控制炭疽病很重要。这项工作的意义在于通过全基因组分析鉴定出直接受AtxA调控的基因。这些结果揭示了炭疽芽孢杆菌致病性基因调控网络的第一层，并为进一步了解炭疽芽孢杆菌提供了有用的资源。
