College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia.
College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia
mSphere. 2019 Feb 20;4(1):e00028-19. doi: 10.1128/mSphereDirect.00028-19.
Insertion sequences (IS) are fundamental mediators of genome plasticity with the potential to generate phenotypic variation with significant evolutionary outcomes. Here, a recently active miniature inverted-repeat transposon element (MITE) was identified in a derivative of ATCC 17978 after being subjected to stress conditions. Transposition of the novel element led to the disruption of the gene, resulting in a characteristic hypermotile phenotype. DNA identity shared between the terminal inverted repeats of this MITE and coresident IS elements, together with the generation of 9-bp target site duplications, provides strong evidence that IS elements were responsible for mobilization of the MITE (designated MITE ) within this strain. A wider genome-level survey identified MITE in 30 additional genomes at various frequencies and one genome. Ninety MITE copies could be identified, of which 40% had target site duplications, indicating recent transposition events. Elements ranged between 111 and 114 bp; 90% were 113 bp in length. Using the MITE consensus sequence, putative outward-facing σ70 promoter sequences in both orientations were identified. The identification of transcripts originating from the promoter in one direction supports the proposal that the element can influence neighboring host gene transcription. The location of MITE varied significantly between and within genomes, preferentially integrating into AT-rich regions. Additionally, a copy of MITE was identified in a novel 8.5-kb composite transposon, Tn, in the CCUG 350 chromosome. Overall, this study shows that MITE is the most abundant nonautonomous element currently found in One of the most important weapons in the armory of is its impressive genetic plasticity, facilitating rapid genetic mutations and rearrangements as well as integration of foreign determinants carried by mobile genetic elements. Of these, IS are considered one of the key forces shaping bacterial genomes and ultimately evolution. We report the identification of a novel nonautonomous IS-derived element present in multiple bacterial species from the family and its recent translocation into the locus in the ATCC 17978 genome. The latter finding adds new knowledge to only a limited number of documented examples of MITEs in the literature and underscores the plastic nature of the locus in MITE , and its predicted parent(s), may be a source of substantial adaptive evolution within environmental and clinically relevant bacterial pathogens and, thus, have broad implications for niche-specific adaptation.
插入序列（IS）是基因组可塑性的基本介质，具有产生具有重大进化结果的表型变异的潜力。在这里，在经受应激条件后，在 ATCC 17978 的衍生物中鉴定出一种新的活性微型反向重复转座子元件（MITE）。该新元件的转座导致 基因的破坏，导致特征性的超运动表型。该 MITE 的末端反向重复序列与共存的 IS 元件之间的 DNA 同一性，以及产生 9 个碱基对的靶位重复，提供了强有力的证据表明 IS 元件负责该菌株中 MITE 的迁移（指定为 MITE ）。更广泛的基因组水平调查在各种频率和一个 基因组中鉴定出 30 个额外的 基因组中的 MITE 。可以鉴定出 90 个 MITE 拷贝，其中 40％具有靶位重复，表明最近发生了转座事件。元件在 111 到 114bp 之间；90％的长度为 113bp。使用 MITE 共识序列，在两个方向上鉴定出向外定向的 σ70 启动子序列。一个方向上源自启动子的转录本的鉴定支持该元件可以影响邻近宿主基因转录的提议。MITE 在基因组之间和内部的位置差异很大，优先整合到富含 AT 的区域。此外，在 CCUG 350 染色体的新型 8.5kb 复合转座子 Tn 中鉴定出 MITE 的一个副本。总体而言，这项研究表明，MITE 是目前在 中发现的最丰富的非自主元件。 的武器库中最重要的武器之一是其令人印象深刻的遗传可塑性，它促进了快速的基因突变和重排以及由移动遗传元件携带的外源决定因素的整合。其中，IS 被认为是塑造细菌基因组并最终进化的关键力量之一。我们报告了在 家族的多个细菌物种中发现的新型非自主 IS 衍生元件的鉴定及其最近在 ATCC 17978 基因组中 基因座的易位。后一发现增加了文献中记录的 MITE 数量有限的文献中的新知识，并强调了 基因座在 MITE 中的可塑性及其预测的亲本，可能是环境和临床相关细菌病原体中大量适应性进化的来源，因此对特定于生态位的适应具有广泛的意义。
