Derivation of Escherichia coli O157:H7 from its O55:H7 precursor.
Derivation of Escherichia coli O157:H7 from its O55:H7 precursor.
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从大肠杆菌 O55:H7 前体衍生出大肠杆菌 O157:H7
DOI：
10.1371/journal.pone.0008700
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发表时间：
2010-01-14
期刊：
影响因子：
3.7
通讯作者：
Wang L
中科院分区：
文献类型：
--
作者：
Zhou Z;Li X;Liu B;Beutin L;Xu J;Ren Y;Feng L;Lan R;Reeves PR;Wang L
现有29个大肠杆菌基因组序列，大多与物种多样性或致病性模式的研究有关，包括众所周知的O157:H7克隆的两个基因组。然而，目前还没有对密切相关的克隆进行旨在揭示进化变化细节的基因组研究。本研究利用已发表的基因组序列，对与主要致病性O157:H7克隆密切相关的O55:H7菌株进行了基因组测序，并进行了比较基因组学和蛋白质组学分析。我们能够将基因组之间的大多数差异分配给特定谱系中的个体突变，重组事件或横向基因转移事件。主要差异包括仅存在于O55:H7染色体中的II型分泌系统，O55:H7中较少的III型分泌系统效应物，O55:H7中有19个噬菌体基因组或噬菌体样元件，而O157:H7中有23个，两者共有的只有3个。在O55:H7和O157:H7谱系中都发现了许多其他变化，但总的来说，O157:H7谱系的变化更多。例如，我们发现O157:H7的同义突变替换比O55:H7多50%。这两个菌株在蛋白质组学水平上也存在分歧。突变的同义snp被用来使用新的时钟速率来估计400年的分化时间，而使用传统的时钟速率则为14,000至70,000年。同样的方法应用于三个密切相关的肠外致病性大肠杆菌基因组，发现了相似水平的突变和重组。这项研究首次揭示了O157:H7克隆从其O55:H7祖先进化的全部事件，并表明O157:H7是最近出现的。我们的研究结果还表明，大肠杆菌相对于突变的重组频率远低于在霍乱弧菌谱系的可比研究中观察到的频率。
There are 29 E. coli genome sequences available, mostly related to studies of species diversity or mode of pathogenicity, including two genomes of the well-known O157:H7 clone. However, there have been no genome studies of closely related clones aimed at exposing the details of evolutionary change. Here we sequenced the genome of an O55:H7 strain, closely related to the major pathogenic O157:H7 clone, with published genome sequences, and undertook comparative genomic and proteomic analysis. We were able to allocate most differences between the genomes to individual mutations, recombination events, or lateral gene transfer events, in specific lineages. Major differences include a type II secretion system present only in the O55:H7 chromosome, fewer type III secretion system effectors in O55:H7, and 19 phage genomes or phagelike elements in O55:H7 compared to 23 in O157:H7, with only three common to both. Many other changes were found in both O55:H7 and O157:H7 lineages, but in general there has been more change in the O157:H7 lineages. For example, we found 50% more synonymous mutational substitutions in O157:H7 compared to O55:H7. The two strains also diverged at the proteomic level. Mutational synonymous SNPs were used to estimate a divergence time of 400 years using a new clock rate, in contrast to 14,000 to 70,000 years using the traditional clock rates. The same approaches were applied to three closely related extraintestinal pathogenic E. coli genomes, and similar levels of mutation and recombination were found. This study revealed for the first time the full range of events involved in the evolution of the O157:H7 clone from its O55:H7 ancestor, and suggested that O157:H7 arose quite recently. Our findings also suggest that E. coli has a much lower frequency of recombination relative to mutation than was observed in a comparable study of a Vibrio cholerae lineage.
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影响因子：
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作者：
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通讯作者：
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影响因子：
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