Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
Division of Infectious Diseases, Brigham and Women's Hospital/Harvard Medical School, 181 Longwood Avenue, Boston, MA, 02115, USA.
Nat Commun. 2022 Jul 23;13(1):4258. doi: 10.1038/s41467-022-31925-w.
Phocaeicola vulgatus is one of the most abundant and ubiquitous bacterial species of the human gut microbiota, yet a comprehensive analysis of antibacterial toxin production by members of this species has not been reported. Here, we identify and characterize a previously undescribed antibacterial protein. This toxin, designated BcpT, is encoded on a small mobile plasmid that is largely confined to strains of the closely related species Phocaeicola vulgatus and Phocaeicola dorei. BcpT is unusual in that it requires cleavage at two distinct sites for activation, and we identify bacterial proteases that perform this activation. We further identify BcpT's receptor as the Lipid A-core glycan, allowing BcpT to target species of other Bacteroidales families. Exposure of cells to BcpT induces a response involving an unusual sigma/anti-sigma factor pair that is likely triggered by cell envelope stress, resulting in the expression of genes that partially protect cells from multiple antimicrobial toxins.
脆弱拟杆菌是人类肠道微生物群中最丰富和无处不在的细菌物种之一，但尚未对该物种成员产生的抗菌毒素进行全面分析。在这里，我们鉴定并描述了一种以前未被描述的抗菌蛋白。这种毒素被命名为 BcpT，它编码在一个小型可移动质粒上，该质粒主要局限于密切相关的脆弱拟杆菌和多雷拟杆菌菌株。BcpT 不同寻常的是，它需要在两个不同的位点切割才能激活，我们鉴定了执行这种激活的细菌蛋白酶。我们进一步确定 BcpT 的受体是脂 A-核心聚糖，使 BcpT 能够靶向其他拟杆菌科的物种。BcpT 暴露于细胞会诱导涉及一种不寻常的 σ/反 σ 因子对的反应，这可能是由细胞包膜应激引发的，导致表达部分保护细胞免受多种抗菌毒素的基因。
