Who ate whom?: Adaptive Helicobacter genomic changes that accompanied a host jump from early humans to large felines
Who ate whom?: Adaptive Helicobacter genomic changes that accompanied a host jump from early humans to large felines
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DOI：
10.1371/journal.pgen.0020120
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发表时间：
2006-07-01
期刊：
影响因子：
4.5
通讯作者：
Schuster, Stephan C.
中科院分区：
文献类型：
--
作者：
Eppinger, Mark;Baar, Claudia;Schuster, Stephan C.
幽门螺杆菌在人类中的感染由来已久，其种群遗传结构反映了远古人类的迁徙。一种关系密切的物种，无爪螺杆菌，专属于大型猫科动物，包括猎豹、狮子和老虎，而与人类关系更密切的宿主拥有更远亲的幽门螺杆菌物种。这一观察结果表明，寄主物种之间存在跳跃。但谁吃了谁，什么时候发生的？为了解决这个问题，我们测定了棘爪螺杆菌Sheeba株的基因组序列，并将其与幽门螺杆菌基因组进行了比较。基因组之间保守的核心基因如此相似，以至于宿主的跳跃可能发生在过去的20万年(范围为5万-40万年)。然而，Sheeba基因组也具有独特的特征，表明宿主跳跃的方向，即从早期的人类到猫。Sheeba拥有异常大量的高度碎片化基因，其中许多编码外膜蛋白，这些基因可能已经被破坏，以绕过猫宿主免疫系统的有害反应。此外，已发现的少数Sheeba特异性基因包括一组编码细菌细胞表面碳水化合物唾液酸化的基因，这些基因是通过水平遗传交换输入的，可能也有助于逃避宿主的免疫防御。这些结果为阐明使细菌适应新的动物宿主的分子事件提供了基因组基础。
Helicobacter pylori infection of humans is so old that its population genetic structure reflects that of ancient human migrations. A closely related species, Helicobacter acinonychis, is specific for large felines, including cheetahs, lions, and tigers, whereas hosts more closely related to humans harbor more distantly related Helicobacter species. This observation suggests a jump between host species. But who ate whom and when did it happen? In order to resolve this question, we determined the genomic sequence of H. acinonychis strain Sheeba and compared it to genomes from H. pylori. The conserved core genes between the genomes are so similar that the host jump probably occurred within the last 200,000 (range 50,000 - 400,000) years. However, the Sheeba genome also possesses unique features that indicate the direction of the host jump, namely from early humans to cats. Sheeba possesses an unusually large number of highly fragmented genes, many encoding outer membrane proteins, which may have been destroyed in order to bypass deleterious responses from the feline host immune system. In addition, the few Sheeba-specific genes that were found include a cluster of genes encoding sialylation of the bacterial cell surface carbohydrates, which were imported by horizontal genetic exchange and might also help to evade host immune defenses. These results provide a genomic basis for elucidating molecular events that allow bacteria to adapt to novel animal hosts.