Bacterial and archaeal genomes encompass numerous operons that typically consist of two to five genes. On larger scales, however, gene order is poorly conserved through the evolution of prokaryotes. Nevertheless, non-random localization of different classes of genes on prokaryotic chromosomes could reflect important functional and evolutionary constraints. We explored the patterns of genomic localization of evolutionarily conserved (ancient) and variable (young) genes across the diversity of bacteria and archaea. Nearly all bacterial and archaeal chromosomes were found to encompass large segments of 100–300 kb that were significantly enriched in either ancient or young genes. Similar clustering of genes with lethal knockout phenotype (essential genes) was observed as well. Mathematical modeling of genome evolution suggests that this long-range gene clustering in prokaryotic chromosomes reflects perpetual genome rearrangement driven by a combination of selective and neutral processes rather than evolutionary conservation.

中文翻译：

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按基因年龄和功能对原核基因组进行长程分割


细菌和古细菌基因组包含许多操纵子，通常由 2 到 5 个基因组成。然而，在更大的尺度上，原核生物的进化过程中基因顺序的保守性很差。然而，不同类别的基因在原核染色体上的非随机定位可能反映了重要的功能和进化限制。我们探索了细菌和古细菌多样性中进化保守（古老）和可变（年轻）基因的基因组定位模式。发现几乎所有细菌和古细菌染色体都包含 100-300 kb 的大片段，这些片段在古老或年轻基因中显着富集。还观察到具有致死性敲除表型 （必需基因） 的类似基因聚集。基因组进化的数学模型表明，原核染色体中的这种长程基因聚集反映了由选择性和中性过程的组合驱动的永久基因组重排，而不是进化保守。