The last eukaryotic common ancestor (LECA): Acquisition of cytoskeletal motility from aerotolerant spirochetes in the Proterozoic Eon
The last eukaryotic common ancestor (LECA): Acquisition of cytoskeletal motility from aerotolerant spirochetes in the Proterozoic Eon
复制标题
DOI：
10.1073/pnas.0604985103
复制
发表时间：
2006-08-29
影响因子：
11.1
通讯作者：
Hall, John
中科院分区：
文献类型：
--
作者：
Margulis, Lynn;Chapman, Michael;Hall, John
我们发展了一个共生的概念起源的真核细胞内运动系统从厌氧但耐氧螺旋体在富含硫化物的环境。最后的真核生物共同祖先（LECA）有现存的古原生生物后代：具有Embden-Meyerhof糖酵解和底物水平磷酸化的运动有核细胞，缺乏α-变形菌共生体，形成了共生体。游泳和调节的O-2-耐受性通过硫化物氧化已经获得了sulfidogenic无壁古细菌（热等离子体）后，耐氧细胞质微管含螺旋体（真细菌）连接到他们。增加稳定性的硫化物氧化/硫还原财团类似于现存的硫syntrophies（Thiodendron）导致融合。真细菌-古细菌的共生成为永久性的细胞核进化的原核重组膜肥大，类似于Gemmata obscuriglobus和其他δ-变形菌与膜结合的类核。组蛋白包被的DNA，蛋白质合成的RNA，氨基酰化，和其他酶的硫化物，而大多数细胞内的运动来自螺旋体。在缺氧和微氧的元古宙生境中，LECA就是从这种氧化还原同营进化而来的。细胞核起源于真细菌和古细菌DNA的重组，这些DNA仍然附着在真细菌的运动结构上，并成为微管细胞骨架，包括有丝分裂器。直接的LECA后代包括在缺氧环境中自由生活的古原生生物：archamoeetris，metamonads，parabasalids和一些哺乳动物与有丝分裂体的共生体。LECA后来通过整合原线粒体获得了完全有氧的克雷布斯循环-氧化磷酸化-线粒体代谢，这是第三种α-蛋白细菌共生体，大多数原生生物的祖先，所有真菌，植物和动物都进化而来。其次，厌氧真核生物在这种呼吸氧气的真细菌整合后从LECA进化而来。阐述了LECA概念的分子生物学解释能力和实验预测。
We develop a symbiogenetic concept of the origin of eukaryotic intracellular motility systems from anaerobic but aerotolerant spirochetes in sulfide-rich environments. The last eukaryotic common ancestors (LECAs) have extant archaeprotist descendants: motile nucleated cells with Embden-Meyerhof glycolysis and substrate-level phosphorylation that lack the alpha-proteobacterial symbiont that became the mitochondrion. Swimming and regulated O-2-tolerance via sulfide oxidation already had been acquired by sulfidogenic wall-less archaebacteria (thermoplasmas) after aerotolerant cytoplasmictubule-containing spirochetes (eubacteria) attached to them. Increasing stability of sulfide-oxidizing/sulfur-reducing consortia analogous to extant sulfur syntrophies (Thiodendron) led to fusion. The eubacteria-archaebacteria symbiosis became permanent as the nucleus evolved by prokaryotic recombination with membrane hypertrophy, analogous to Gemmata obscuriglobus and other delta-proteobacteria with membrane-bounded nucleoids. Histone-coated DNA, protein-synthetic RNAs, amino-acylating, and other enzymes were contributed by the sulfidogen whereas most intracellular motility derives from the spirochete. From this redox syntrophy in anoxic and microoxic Proterozoic habitats LECA evolved. The nucleus originated by recombination of eu- and archaebacterial DNA that remained attached to eubacterial motility structures and became the microtubular cytoskeleton, including the mitotic apparatus. Direct LECA descendants include free-living archaeprotists in anoxic environments: archamoebae, metamonads, parabasalids, and some mammalian symbionts with mitosomes. LECA later acquired the fully aerobic Krebs cycle-oxidative phosphorylation-mitochondrial metabolism by integration of the protomitochondrion, a third alpha-proteolbacterial symbiont from which the ancestors to most protoctists, all fungi, plants, and animals evolved. Secondarily anaerobic eukaryotes descended from LECA after integration of this oxygen-respiring eubacterium. Explanatory power and experimental predictions for molecular biology of the LECA concept are stated.