Type III secretion systems and the evolution of mutualistic endosymbiosis
Type III secretion systems and the evolution of mutualistic endosymbiosis
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DOI：
10.1073/pnas.182213299
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发表时间：
2002-09-17
影响因子：
11.1
通讯作者：
Moran, NA
中科院分区：
文献类型：
--
作者：
Dale, C;Plague, GR;Moran, NA
寄生虫可以与宿主发展合作共生关系的观点既有吸引力，也被广泛接受；然而，没有分子遗传学证据表明这种转变。在这里，我们证明了谷物象甲的互惠细菌内共生体维持和表达inv/spa基因，编码与细菌病原体入侵同源的III型分泌系统。系统发育分析表明，inv/spa基因存在于象虫内共生体的前共生祖先中，至少发生在5000万年前。Inv/spa基因在维持共生中的作用是通过它们在体内和体外的表达上调来证明的，这些条件与宿主细胞的入侵相一致。
The view that parasites can develop cooperative symbiotic relationships with their hosts is both appealing and widely held; however, there is no molecular genetic evidence of such a transition. Here we demonstrate that a mutualistic bacterial endosymbiont of grain weevils maintains and expresses inv/spa genes encoding a type III secretion system homologous to that used for invasion by bacterial pathogens. Phylogenetic analyses indicate that inv/spa genes were present in presymbiotic ancestors of the weevil endosymbionts, occurring at least 50 million years ago. The function of inv/spa genes in maintaining symbiosis is demonstrated by the up-regulation of their expression under both in vivo and in vitro conditions that coincide with host cell invasion.