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首页> 外文期刊>Journal of bacteriology >Genomic Instability in Regions Adjacent to a Highly Conserved pch Prophage in Escherichia coli O157:H7 Generates Diversity in Expression Patterns of the LEE Pathogenicity Island
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Genomic Instability in Regions Adjacent to a Highly Conserved pch Prophage in Escherichia coli O157:H7 Generates Diversity in Expression Patterns of the LEE Pathogenicity Island

机译：在大肠杆菌O157：H7中高度保守的pch噬菌体附近的区域中的基因组不稳定性会在LEE致病岛的表达模式中产生多样性

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The LEE pathogenicity island has been acquired on multiple occasions within the different lineages of enteropathogenic and enterohemorrhagic Escherichia coli. In each lineage, LEE expression is regulated by complex networks of pathways, including core pathways shared by all lineages and lineage-specific pathways. Within the O157:H7 lineage of enterohemorrhagic E. coli, strain-to-strain variation in LEE expression has been observed, implying that expression patterns can diversify even within highly related subpopulations. Using comparative genomics of E. coli O157:H7 subpopulations, we have identified one source of strain-level variation affecting LEE expression. The variation occurs in prophage-dense regions of the genome that lie immediately adjacent to the late regions of the pch prophage carrying pchA, pchB, pchC, and a newly identified pch gene, pchX. Genomic segments extending from the holin S region to the pchA, pchB, pchC, and pchX genes of their respective prophage are highly conserved but are nonetheless embedded within adjacent genomic segments that are extraordinarily variable, termed pch adjacent genomic regions (pch AGR). Despite the remarkable degree of variation, the pattern of variation in pch AGR is highly correlated with the distribution of phylogenetic markers on the backbone of the genome. Quantitative analysis of transcription from the LEE1 promoter further revealed that variation in the pch AGR has substantial effects on absolute levels and patterns of LEE1 transcription. Variation in the pch AGR therefore serves as a mechanism to diversify LEE expression patterns, and the lineage-specific pattern of pch AGR variation could ultimately influence ecological or virulence characteristics of subpopulations within each lineage.
机译：LEE致病岛已在肠致病性和肠出血性大肠埃希氏菌的不同谱系中多次获得。在每个谱系中，LEE表达受复杂的通路网络调节，包括所有谱系共有的核心通路和特定于谱系的通路。在肠出血性大肠杆菌（E）的O157：H7血统内。在大肠杆菌中，已观察到LEE表达在不同菌株之间的变异，这表明即使在高度相关的亚种群中，表达模式也可以多样化。使用 E的比较基因组学。大肠杆菌O157：H7亚群，我们确定了影响LEE表达的菌株水平变异的一种来源。变异发生在基因组的密集密集区域中，该区域紧靠带有 pchA，pchB，pchC 的 pch 噬菌体晚期区域和新识别的 pch 基因， pchX 。从holin S区域延伸到其各自prophage的 pchA，pchB，pchC 和 pchX 基因的基因组区段是高度保守的，但仍嵌入在相邻的基因组区段中异常可变，称为 pch 相邻基因组区域（ pch AGR）。尽管变异程度显着，但 pch AGR的变异模式与基因组骨架上系统发生标记的分布高度相关。 LEE1 启动子转录的定量分析进一步表明， pch AGR中的变异对LEE1转录的绝对水平和模式有重大影响。因此， pch AGR的变异是使LEE表达模式多样化的一种机制，而 pch AGR变异的特定于谱系的格局最终可能影响亚种内亚种群的生态或毒力特征。每个血统。

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