A new α-proteobacterial clade of Bdellovibrio-like predators:: implications for the mitochondrial endosymbiotic theory
A new α-proteobacterial clade of Bdellovibrio-like predators:: implications for the mitochondrial endosymbiotic theory
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DOI：
10.1111/j.1462-2920.2006.01101.x
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发表时间：
2006-12-01
影响因子：
5.1
通讯作者：
Jurkevitch, Edouard
中科院分区：
文献类型：
--
作者：
Davidov, Yaacov;Huchon, Dorothee;Jurkevitch, Edouard
蛭弧菌及类蛭弧菌是一类特殊的、普遍存在的、体积小、运动性强的革兰氏阴性细菌，是其他细菌的天敌。通常，这些捕食者侵入猎物的周质，在那里它们生长和繁殖。迄今为止，BALO构成了两个高度多样化的家庭隶属于三角洲-变形菌纲。在这项研究中，Micavibrio spp.，从土壤中分离出一个BALO谱系的表生捕食者。这些细菌附着在其他原核生物的消化和生长上，就像其他BALO一样。基于六个基因的多重系统发育分析显示，它们在α-变形菌中形成了一个深分支，不隶属于任何α-变形菌目。BALO在α-变形菌中的存在表明，它们独特的寄生模式可能是这类变形菌的祖先特征。从α-变形杆菌内共生体的起源是强烈支持的分子生物学。越来越多的数据表明，内共生体的宿主也是原核生物。由于原核生物不能吞噬，内共生体进入宿主的方式仍然是个谜。在这里，我们提出了一个方案的基础上BALO喂养模式假设的线粒体内共生的起源在发挥作用的机制。
Bdellovibrio-and-like organisms (BALOs) are peculiar, ubiquitous, small-sized, highly motile Gram-negative bacteria that are obligatory predators of other bacteria. Typically, these predators invade the periplasm of their prey where they grow and replicate. To date, BALOs constitute two highly diverse families affiliated with the delta-proteobacteria class. In this study, Micavibrio spp., a BALO lineage of epibiotic predators, were isolated from soil. These bacteria attach to digest and grow at the expense of other prokaryotes, much like other BALOs. Multiple phylogenetic analyses based on six genes revealed that they formed a deep branch within the alpha-proteobacteria, not affiliated with any of the alpha-proteobacterial orders. The presence of BALOs deep among the alpha-proteobacteria suggests that their peculiar mode of parasitism maybe an ancestral character in this proteobacterial class. The origin of the mitochondrion from an alpha-proteobacterium endosymbiont is strongly supported by molecular phylogenies. Accumulating data suggest that the endosymbiont's host was also a prokaryote. As prokaryotes are unable to phagocytose, the means by which the endosymbiont gained access into its host remains mysterious. We here propose a scenario based on the BALO feeding-mode to hypothesize a mechanism at play at the origin of the mitochondrial endosymbiosis.