Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F., Mexico.
FEMS Microbiol Rev. 2010 Jan;34(1):59-86. doi: 10.1111/j.1574-6976.2009.00196.x.
The study of genomic organization and regulatory elements of rRNA genes in metazoan paradigmatic organisms has led to the most accepted model of rRNA gene organization in eukaryotes. Nevertheless, the rRNA genes of microbial eukaryotes have also been studied in considerable detail and their atypical structures have been considered as exceptions. However, it is likely that these organisms have preserved variations in the organization of a versatile gene that may be seen as living records of evolution. Here, we review the organization of the main rRNA transcription unit (rDNA) and the 5S rRNA genes (5S rDNA). These genes are reiterated in the genome of microbial eukaryotes and may be coded alone, in tandem repeats, linked to each other or linked to other genes. They may be found in the chromosome or extrachromosomally in linear or circular units. rDNA coding regions may contain introns, sequence insertions, protein-coding genes or additional spacers. The 5S rDNA can be found in tandem repeats or genetically linked to genes transcribed by RNA polymerases I, II or III. Available information from about a hundred microbial eukaryotes was used to review the unexpected diversity in the genomic organization of rRNA genes.
对后生动物典范生物的 rRNA 基因的基因组组织和调控元件的研究，导致了真核生物中最被接受的 rRNA 基因组织模型。然而，微生物真核生物的 rRNA 基因也得到了相当详细的研究，它们的非典型结构被认为是例外。然而，这些生物体可能保留了多功能基因组织的变化，这些变化可能被视为进化的活记录。在这里，我们回顾了主要 rRNA 转录单位（rDNA）和 5S rRNA 基因（5S rDNA）的组织。这些基因在微生物真核生物的基因组中重复出现，可能单独编码，串联重复，彼此相连或与其他基因相连。它们可能存在于染色体上，也可能以线性或圆形单位存在于染色体外。rDNA 编码区可能含有内含子、序列插入、编码蛋白质的基因或额外的间隔区。5S rDNA 可以串联重复，或者与由 RNA 聚合酶 I、II 或 III 转录的基因在遗传上相连。利用大约一百种微生物真核生物的现有信息，我们回顾了 rRNA 基因在基因组组织上出人意料的多样性。
