Bell Philip J L
Microbiogen Pty Ltd., Sydney, NSW, Australia.
Front Microbiol. 2022 May 11;13:858064. doi: 10.3389/fmicb.2022.858064. eCollection 2022.
Although it is widely taught that all modern life descended modification from a last universal common ancestor (LUCA), this dominant paradigm is yet to provide a generally accepted explanation for the chasm in design between prokaryotic and eukaryotic cells. Counter to this dominant paradigm, the viral eukaryogenesis (VE) hypothesis proposes that the eukaryotes originated as an emergent superorganism and thus did not evolve from LUCA descent with incremental modification. According to the VE hypothesis, the eukaryotic nucleus descends from a viral factory, the mitochondrion descends from an enslaved alpha-proteobacteria and the cytoplasm and plasma membrane descend from an archaeal host. A virus initiated the eukaryogenesis process by colonising an archaeal host to create a virocell that had its metabolism reprogrammed to support the viral factory. Subsequently, viral processes facilitated the entry of a bacterium into the archaeal cytoplasm which was also eventually reprogrammed to support the viral factory. As the viral factory increased control of the consortium, the archaeal genome was lost, the bacterial genome was greatly reduced and the viral factory eventually evolved into the nucleus. It is proposed that the interaction between these three simple components generated a superorganism whose emergent properties allowed the evolution of eukaryotic complexity. If the radical tenets of the VE hypothesis are ultimately accepted, current biological paradigms regarding viruses, cell theory, LUCA and the universal Tree of Life (ToL) should be fundamentally altered or completely abandoned.
尽管人们普遍认为，所有现代生命都是由最后一个共同祖先（LUCA）经过修饰演化而来，但这一主流范式尚未对原核细胞和真核细胞在设计上的巨大差异给出一个被广泛接受的解释。与这一主流范式相反，病毒真核生物发生（VE）假说提出，真核生物起源于一种新兴的超级生物体，因此并非从LUCA经过逐步修饰演化而来。根据VE假说，真核细胞核起源于一个病毒工厂，线粒体起源于被奴役的α-变形菌，细胞质和质膜起源于古菌宿主。一种病毒通过侵染古菌宿主启动了真核生物发生过程，从而创造出一个病毒细胞，其新陈代谢被重新编程以支持病毒工厂。随后，病毒过程促使一种细菌进入古菌细胞质，而后者最终也被重新编程以支持病毒工厂。随着病毒工厂对这个联合体的控制增强，古菌基因组丢失，细菌基因组大幅缩减，病毒工厂最终演化成细胞核。有人提出，这三个简单成分之间的相互作用产生了一种超级生物体，其涌现特性使得真核生物的复杂性得以进化。如果VE假说的激进信条最终被接受，那么当前关于病毒、细胞学说、LUCA以及通用生命树（ToL）的生物学范式应该从根本上被改变或完全摒弃。
