Lecompte Odile, Ripp Raymond, Thierry Jean-Claude, Moras Dino, Poch Olivier
Laboratoire de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire (CNRS, INSERM, ULP), BP163, 67404 Illkirch Cedex, France.
Nucleic Acids Res. 2002 Dec 15;30(24):5382-90. doi: 10.1093/nar/gkf693.
A comprehensive investigation of ribosomal genes in complete genomes from 66 different species allows us to address the distribution of r-proteins between and within the three primary domains. Thirty-four r-protein families are represented in all domains but 33 families are specific to Archaea and Eucarya, providing evidence for specialisation at an early stage of evolution between the bacterial lineage and the lineage leading to Archaea and Eukaryotes. With only one specific r-protein, the archaeal ribosome appears to be a small-scale model of the eukaryotic one in terms of protein composition. However, the mechanism of evolution of the protein component of the ribosome appears dramatically different in Archaea. In Bacteria and Eucarya, a restricted number of ribosomal genes can be lost with a bias toward losses in intracellular pathogens. In Archaea, losses implicate 15% of the ribosomal genes revealing an unexpected plasticity of the translation apparatus and the pattern of gene losses indicates a progressive elimination of ribosomal genes in the course of archaeal evolution. This first documented case of reductive evolution at the domain scale provides a new framework for discussing the shape of the universal tree of life and the selective forces directing the evolution of prokaryotes.
对66种不同物种的完整基因组中的核糖体基因进行全面研究，使我们能够探讨核糖体蛋白在三个主要结构域之间以及结构域内部的分布情况。34个核糖体蛋白家族在所有结构域中均有体现，但有33个家族是古细菌和真核生物所特有的，这为细菌谱系与导致古细菌和真核生物的谱系在进化早期的特化提供了证据。仅有一种特定的核糖体蛋白，就古细菌核糖体的蛋白质组成而言，它似乎是真核生物核糖体的一个小规模模型。然而，核糖体蛋白质成分的进化机制在古细菌中似乎有显著不同。在细菌和真核生物中，数量有限的核糖体基因可能会丢失，且偏向于细胞内病原体中的丢失情况。在古细菌中，丢失的核糖体基因占15%，这揭示了翻译装置出乎意料的可塑性，并且基因丢失模式表明在古细菌进化过程中核糖体基因在逐渐被消除。这一首次记录在案的结构域规模的简化进化案例为讨论生命之树的形态以及指导原核生物进化的选择力提供了一个新的框架。
