Department of Clinical Microbiology and Immunology, School of Medicine, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, Israel.
Center for Genomics and Bioinformatics Indiana University, Bloomington, Indiana, United States of America.
PLoS Biol. 2024 Sep 3;22(9):e3002734. doi: 10.1371/journal.pbio.3002734. eCollection 2024 Sep.
Vibrio coralliilyticus is a pathogen of coral and shellfish, leading to devastating economic and ecological consequences worldwide. Although rising ocean temperatures correlate with increased V. coralliilyticus pathogenicity, the specific molecular mechanisms and determinants contributing to virulence remain poorly understood. Here, we systematically analyzed the type VI secretion system (T6SS), a contact-dependent toxin delivery apparatus, in V. coralliilyticus. We identified 2 omnipresent T6SSs that are activated at temperatures in which V. coralliilyticus becomes virulent; T6SS1 is an antibacterial system mediating interbacterial competition, whereas T6SS2 mediates anti-eukaryotic toxicity and contributes to mortality during infection of an aquatic model organism, Artemia salina. Using comparative proteomics, we identified the T6SS1 and T6SS2 toxin arsenals of 3 V. coralliilyticus strains with distinct disease etiologies. Remarkably, T6SS2 secretes at least 9 novel anti-eukaryotic toxins comprising core and accessory repertoires. We propose that T6SSs differently contribute to V. coralliilyticus's virulence: T6SS2 plays a direct role by targeting the host, while T6SS1 plays an indirect role by eliminating competitors.
珊瑚弧菌是珊瑚和贝类的病原体，在全球范围内造成了毁灭性的经济和生态后果。尽管海洋温度升高与珊瑚弧菌致病性增加相关，但导致其毒力的具体分子机制和决定因素仍知之甚少。在这里，我们系统地分析了珊瑚弧菌中的 VI 型分泌系统（T6SS），这是一种接触依赖性毒素输送装置。我们鉴定出 2 种普遍存在的 T6SS，它们在珊瑚弧菌变得具有致病性的温度下被激活；T6SS1 是一种介导细菌间竞争的抗菌系统，而 T6SS2 介导抗真核毒性，并有助于水生模式生物卤虫在感染期间的死亡率。通过比较蛋白质组学，我们鉴定了 3 种具有不同疾病病因的珊瑚弧菌菌株的 T6SS1 和 T6SS2 毒素库。值得注意的是，T6SS2 至少分泌了 9 种新型抗真核毒素，包括核心和辅助库。我们提出 T6SS 以不同的方式有助于珊瑚弧菌的毒力：T6SS2 通过靶向宿主直接发挥作用，而 T6SS1 通过消除竞争者间接发挥作用。
