Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile.
Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile.
Microb Genom. 2023 Apr;9(4). doi: 10.1099/mgen.0.000973.
is the leading cause of seafood-borne gastroenteritis worldwide. A distinctive feature of the O3:K6 pandemic clone, and its derivatives, is the presence of a second, phylogenetically distinct, type III secretion system (T3SS2) encoded within the genomic island VPaI-7. The T3SS2 allows the delivery of effector proteins directly into the cytosol of infected eukaryotic cells to subvert key host-cell processes, critical for to colonize and cause disease. Furthermore, the T3SS2 also increases the environmental fitness of in its interaction with bacterivorous protists; hence, it has been proposed that it contributed to the global oceanic spread of the pandemic clone. Several reports have identified T3SS2-related genes in and non- species, suggesting that the T3SS2 gene cluster is not restricted to the and can mobilize through horizontal gene transfer events. In this work, we performed a large-scale genomic analysis to determine the phylogenetic distribution of the T3SS2 gene cluster and its repertoire of effector proteins. We identified putative T3SS2 gene clusters in 1130 bacterial genomes from 8 bacterial genera, 5 bacterial families and 47 bacterial species. A hierarchical clustering analysis allowed us to define six T3SS2 subgroups (I-VI) with different repertoires of effector proteins, redefining the concepts of T3SS2 core and accessory effector proteins. Finally, we identified a subset of the T3SS2 gene clusters (subgroup VI) that lacks most T3SS2 effector proteins described to date and provided a list of 10 novel effector candidates for this subgroup through bioinformatic analysis. Collectively, our findings indicate that the T3SS2 extends beyond the family and suggest that different effector protein repertories could have a differential impact on the pathogenic potential and environmental fitness of each bacterium that has acquired the T3SS2 gene cluster.
创伤弧菌是全球食源性肠胃炎的主要致病菌。O3:K6 大流行克隆及其衍生株的一个显著特征是，基因组岛 VPaI-7 内存在第二个系统进化上不同的 III 型分泌系统 (T3SS2)。T3SS2 允许将效应蛋白直接递送至被感染真核细胞的细胞质中，从而颠覆宿主细胞的关键过程，这对于弧菌定植和致病至关重要。此外，T3SS2 还增加了弧菌在与噬菌原生动物相互作用时的环境适应性；因此，有人提出它促成了大流行克隆在全球海洋中的传播。有几项报告在弧菌和非弧菌种中鉴定出了 T3SS2 相关基因，表明 T3SS2 基因簇不仅限于弧菌，并且可以通过水平基因转移事件进行移动。在这项工作中，我们进行了大规模基因组分析，以确定 T3SS2 基因簇的系统发育分布及其效应蛋白的组成。我们在来自 8 个细菌属、5 个细菌科和 47 个细菌种的 1130 个细菌基因组中鉴定出了推定的 T3SS2 基因簇。层次聚类分析使我们能够定义具有不同效应蛋白组成的六个 T3SS2 亚组 (I-VI)，重新定义了 T3SS2 核心和辅助效应蛋白的概念。最后，我们确定了 T3SS2 基因簇的一个亚组 (亚组 VI)，该亚组缺乏迄今为止描述的大多数 T3SS2 效应蛋白，并通过生物信息学分析为该亚组提供了 10 个新的效应蛋白候选物。总的来说，我们的研究结果表明 T3SS2 超出了弧菌科的范围，并表明不同的效应蛋白组成可能对获得 T3SS2 基因簇的每种细菌的致病潜力和环境适应性产生不同的影响。
