Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, UK.
Microb Genom. 2023 Jun;9(6). doi: 10.1099/mgen.0.001036.
The type VIIb protein secretion system (T7SSb) is found in (firmicute) bacteria and has been shown to mediate interbacterial competition. EssC is a membrane-bound ATPase that is a critical component of the T7SSb and plays a key role in substrate recognition. Prior analysis of available genome sequences of the foodborne bacterial pathogen has shown that although the T7SSb was encoded as part of the core genome, EssC could be found as one of seven different sequence variants. While each sequence variant was associated with a specific suite of candidate substrate proteins encoded immediately downstream of , many LXG-domain proteins were encoded across multiple sequence variants. Here, we have extended this analysis using a diverse collection of 37 930 . genomes. We have identified a rare eighth variant of EssC present in ten lineage III genomes. These genomes also encode a large toxin of the rearrangement hotspot (Rhs) repeat family adjacent to , along with a probable immunity protein and three small accessory proteins. We have further identified nine novel LXG-domain proteins, and four additional chromosomal hotspots across genomes where LXG proteins can be encoded. The eight EssC variants were also found in other species, with additional novel EssC types also identified. Across the genus, species frequently encoded multiple EssC types, indicating that T7SSb diversity is a primary feature of the genus .
VIIb 型蛋白分泌系统（T7SSb）存在于（厚壁菌门）细菌中，已被证明可介导细菌间的竞争。EssC 是一种膜结合的 ATP 酶，是 T7SSb 的关键组成部分，在底物识别中发挥着关键作用。对食源性病原体的现有基因组序列的先前分析表明，尽管 T7SSb 作为核心基因组的一部分被编码，但 EssC 可以作为七种不同序列变体之一找到。虽然每个序列变体都与编码在 下游的特定候选底物蛋白组相关联，但许多 LXG 结构域蛋白在多个 序列变体中被编码。在这里，我们使用来自 37930 个不同的 基因组的多样化集合扩展了这项分析。我们已经在十个 谱系 III 基因组中发现了 EssC 的罕见第八个变体。这些基因组还编码了 Rhs 重复家族的大型毒素，该毒素紧邻 ，以及可能的免疫蛋白和三个小辅助蛋白。我们还进一步鉴定了九个新的 LXG 结构域蛋白，以及在 基因组中可以编码 LXG 蛋白的四个其他染色体热点。这八个 EssC 变体也存在于其他 物种中，还鉴定了其他新的 EssC 类型。在整个属中，物种经常编码多个 EssC 类型，表明 T7SSb 的多样性是该属的主要特征。
