Research Abstract


The origin of a primordial genome through spontaneous symmetry breaking

2017年8月15日 Nature Communications 8 : 250 doi: 10.1038/s41467-017-00243-x (2017)


Nobuto Takeuchi, Paulien Hogeweg and Kunihiko Kaneko

Corresponding Author

竹内 信人
東京大学大学院 総合文化研究科 広域科学専攻 相関基礎科学系

The heredity of a cell is provided by a small number of non-catalytic templates—the genome. How did genomes originate? Here, we demonstrate the possibility that genome-like molecules arise from symmetry breaking between complementary strands of self-replicating molecules. Our model assumes a population of protocells, each containing a population of self-replicating catalytic molecules. The protocells evolve towards maximising the catalytic activities of the molecules to increase their growth rates. Conversely, the molecules evolve towards minimising their catalytic activities to increase their intracellular relative fitness. These conflicting tendencies induce the symmetry breaking, whereby one strand of the molecules remains catalytic and increases its copy number (enzyme-like molecules), whereas the other becomes non-catalytic and decreases its copy number (genome-like molecules). This asymmetry increases the equilibrium cellular fitness by decreasing mutation pressure and increasing intracellular genetic drift. These results implicate conflicting multilevel evolution as a key cause of the origin of genetic complexity.