The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems.
The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems.
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DOI：
10.1371/journal.pgen.1002983
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发表时间：
2012-09
期刊：
影响因子：
4.5
通讯作者：
Rocha EP
中科院分区：
文献类型：
--
作者：
Abby SS;Rocha EP
3型分泌系统（T3SS）是两种复杂细菌机制的重要组成部分：鞭毛驱动细胞运动，非鞭毛T3SS （NF-T3SS）将效应器输送到真核细胞中。然而，这些机器的起源、专业化和多样化仍然不清楚。我们开发了计算工具来识别两个系统的同源成分并区分它们。我们对1000个基因组的分析鉴定出921个t3ss，其中包括222个nf - t3ss。这些系统的系统基因组学和比较分析表明，NF-T3SS起源于鞭毛的缺失，即鞭毛结构的一部分被募集用于新的蛋白质传递功能的进化。这种重构的摘取过程年表至少分两步进行。NF-T3SS的一个中间祖先形式，其后代仍然存在于粘球菌中，缺乏运动所必需的元素，并包括NF-T3SS特征的一个子集。我们认为这个祖先版本参与了蛋白质易位。NF-T3SS进化的第二个主要步骤是通过向NF-T3SS募集分泌素，这一事件在不同的系统中至少发生了三次。在根瘤菌中，分泌素的部分同源基因替换导致两个功能互补的基因。分泌素的获得之后，产生的nf - t3ss迅速适应了多个不同的真核细胞包膜，在那里它们成为原核生物和真核生物之间寄生和互惠关联的关键。我们的工作阐明了导致现存nf - t3ss的进化场景的主要步骤。它展示了分子进化如何通过从其他分子系统中连续删除、创新和招募，将一个复杂的分子机器转化为另一个同样复杂的机器。大多数可移动的细菌使用鞭毛来移动。鞭毛的细胞外成分由其自身的3型分泌系统（T3SS）分泌。非鞭毛T3SS (NF-T3SS)，也被称为注射体，包含许多与鞭毛成分同源的蛋白质。nf - t3ss被许多植物和动物病原体用来向宿主细胞传递效应物，包括毒素。nf - t3ss是一种复杂的蛋白质机器，具有bbb15成分，将细菌细胞包膜连接到真核细胞膜，包括中间的细胞外空间。在这项研究中，我们设计了计算工具来区分鞭毛和nf - t3ss与其他细菌蛋白质序列。研究表明，nf - t3ss是通过一系列基因缺失、创新和从其他细胞结构中吸收成分而从鞭毛进化而来的。我们的进化分析表明，nf - t3ss随后迅速适应了不同的真核细胞，同时保持了与鞭毛高度相似的核心结构。这是一个进化修修补补的例子，一个复杂的结构是通过摘取而产生的，这些元素最初是为其他细胞结构的其他功能而进化的。
Type 3 secretion systems (T3SSs) are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS), which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems. Most motile bacteria use a flagellum to move. The extracellular components of flagella are secreted by their own Type 3 Secretion System (T3SS). The non-flagellar T3SS (NF-T3SS), also named injectisome, includes many proteins that are homologous to flagellar components. NF-T3SSs are employed by many plant and animal pathogens to deliver effectors to host cells, including toxins. NF-T3SSs are complex protein machineries with >15 components that connect bacterial cell envelopes to eukaryotic cell membranes, including the intervening extracellular space. In this study, we designed computational tools to distinguish flagella and NF-T3SSs from other bacterial protein sequences. We show that NF-T3SSs evolved from the flagellum by a series of genetic deletions, innovations, and recruitments of components from other cellular structures. Our evolutionary analysis suggests that NF-T3SSs then quickly adapted to different eukaryotic cells while maintaining a core structure that remains highly similar to the flagellum. This is an example of evolutionary tinkering where a complex structure arises by exaptation, the recruitment of elements that evolved initially for other functions in other cellular structures.
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DOI：
10.1083/jcb.147.3.683
发表时间：
1999-11-01
期刊：
The Journal of cell biology
影响因子：
--
作者：
Blocker A;Gounon P;Larquet E;Niebuhr K;Cabiaux V;Parsot C;Sansonetti P
通讯作者：
Sansonetti P
影响因子：
5.8
作者：
Chevenet, Francois;Croce, Olivier;Berry, Vincent
通讯作者：
Berry, Vincent
DOI：
10.1073/pnas.182213299
发表时间：
2002-09-17
影响因子：
11.1
作者：
Dale, C;Plague, GR;Moran, NA
通讯作者：
Moran, NA
影响因子：
3.2
作者：
Charkowski, AO;Huang, HC;Collmer, A
通讯作者：
Collmer, A
影响因子：
5.2
作者：
Betts-Hampikian HJ;Fields KA
通讯作者：
Fields KA