Barba-Aliaga Marina, Alepuz Paula, Pérez-Ortín José E
Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, València, Spain.
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, València, Spain.
Front Mol Biosci. 2021 Apr 21;8:663209. doi: 10.3389/fmolb.2021.663209. eCollection 2021.
In eukaryotic cells, three nuclear RNA polymerases (RNA pols) carry out the transcription from DNA to RNA, and they all seem to have evolved from a single enzyme present in the common ancestor with archaea. The multiplicity of eukaryotic RNA pols allows each one to remain specialized in the synthesis of a subset of transcripts, which are different in the function, length, cell abundance, diversity, and promoter organization of the corresponding genes. We hypothesize that this specialization of RNA pols has conditioned the evolution of the regulatory mechanisms used to transcribe each gene subset to cope with environmental changes. We herein present the example of the homeostatic regulation of transcript levels changes in cell volume. We propose that the diversity and instability of messenger RNAs, transcribed by RNA polymerase II, have conditioned the appearance of regulatory mechanisms based on different gene promoter strength and mRNA stability. However, for the regulation of ribosomal RNA levels, which are very stable and transcribed mainly by RNA polymerase I from only one promoter, different mechanisms act based on gene copy variation, and a much simpler regulation of the synthesis rate.
在真核细胞中，三种核RNA聚合酶（RNA pols）负责从DNA转录为RNA，它们似乎都从与古细菌的共同祖先中存在的单一酶进化而来。真核RNA聚合酶的多样性使得每种酶都能专门负责合成一部分转录本，这些转录本在相应基因的功能、长度、细胞丰度、多样性和启动子组织方面存在差异。我们假设，RNA聚合酶的这种专业化决定了用于转录每个基因子集以应对环境变化的调控机制的进化。我们在此给出转录水平稳态调节的例子——细胞体积变化。我们提出，由RNA聚合酶II转录的信使RNA的多样性和不稳定性决定了基于不同基因启动子强度和mRNA稳定性的调控机制的出现。然而，对于核糖体RNA水平的调节，核糖体RNA非常稳定，主要由RNA聚合酶I从单一启动子转录，基于基因拷贝变异会有不同的机制起作用，并且合成速率的调节要简单得多。
