Genomic comparison between Salmonella Gallinarum and Pullorum: differential pseudogene formation under common host restriction.
Genomic comparison between Salmonella Gallinarum and Pullorum: differential pseudogene formation under common host restriction.
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DOI：
10.1371/journal.pone.0059427
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Liu SL
中科院分区：
文献类型：
--
作者：
Feng Y;Johnston RN;Liu GR;Liu SL
肠道沙门氏菌和鸡沙门氏菌密切相关，但它们的宿主范围非常不同：前者是宿主混杂的，后者只能感染家禽。它们的基因组序列的比较表明，鸡比肠杆菌经历了更广泛的降解。在其他宿主限制性沙门氏菌血清型中也观察到这种现象，如伤寒和甲型副伤寒。鸡血清型可以进一步分为两个生物型：鸡血清型和鸡白痢，它们以家禽为共同宿主，但引起不同的疾病，前者引起伤寒，后者是痢疾病原体。这两种病原体的基因组比较，重点是假基因，将提供深入了解的进化过程，可能促进了宿主限制性沙门氏菌病原体的形成。我们对鸡白痢菌株的全基因组进行了测序，并与鸡白痢菌和其他沙门氏菌谱系进行了比较。鸡白痢和鸡白痢的基因含量高度相似，但它们的假基因组成有很大差异。大约四分之一的假基因在鸡和鸡白痢中具有相同的失活突变，但这些基因在肠炎中保持完整，这表明祖先鸡可能已经局限于家禽。另一方面，其余的假基因要么在相同的基因中，但具有不同的失活位点，要么是鸡或鸡白痢所特有的，反映了感染家禽时不必要的功能。我们的研究结果支持了这一假设，鸡和鸡白痢的分歧是由主机限制启动和促进。基因组降解的主要形式是假基因的形成，而不是基因的缺失。鉴于鸡白痢和鸡白痢的分歧历史较短，宿主限制对基因组降解的影响是巨大而迅速的，而且这种影响似乎正在继续发挥作用。假基因可能反映了沙门氏菌在家禽宿主中不必要的功能。
Salmonella serovars Enteritidis and Gallinarum are closely related, but their host ranges are very different: the former is host-promiscuous and the latter can infect poultry only. Comparison of their genomic sequences reveals that Gallinarum has undergone much more extensive degradation than Enteritidis. This phenomenon has also been observed in other host restricted Salmonella serovars, such as Typhi and Paratyphi A. The serovar Gallinarum can be further split into two biovars: Gallinarum and Pullorum, which take poultry as their common host but cause distinct diseases, with the former eliciting typhoid and the latter being a dysentery agent. Genomic comparison of the two pathogens, with a focus on pseudogenes, would provide insights into the evolutionary processes that might have facilitated the formation of host-restricted Salmonella pathogens. We sequenced the complete genome of Pullorum strains and made comparison with Gallinarum and other Salmonella lineages. The gene contents of Gallinarum and Pullorum were highly similar, but their pseudogene compositions differed considerably. About one fourth of pseudogenes had the same inactivation mutations in Gallinarum and Pullorum but these genes remained intact in Enteritidis, suggesting that the ancestral Gallinarum may have already been restricted to poultry. On the other hand, the remaining pseudogenes were either in the same genes but with different inactivation sites or unique to Gallinarum or Pullorum, reflecting unnecessary functions in infecting poultry. Our results support the hypothesis that the divergence between Gallinarum and Pullorum was initiated and facilitated by host restriction. Formation of pseudogenes instead of gene deletion is the major form of genomic degradation. Given the short divergence history of Gallinarum and Pullorum, the effect of host restriction on genomic degradation is huge and rapid, and such effect seems to be continuing to work. The pseudogenes may reflect the unnecessary functions for Salmonella within the poultry host.
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影响因子：
14.9
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影响因子：
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通讯作者：
Zagnitko O