Archambault J, Friesen J D
Department of Genetics, Hospital for Sick Children, Toronto, Ontario, Canada.
Microbiol Rev. 1993 Sep;57(3):703-24. doi: 10.1128/mr.57.3.703-724.1993.
The transcription of nucleus-encoded genes in eukaryotes is performed by three distinct RNA polymerases termed I, II, and III, each of which is a complex enzyme composed of more than 10 subunits. The isolation of genes encoding subunits of eukaryotic RNA polymerases from a wide spectrum of organisms has confirmed previous biochemical and immunological data indicating that all three enzymes are closely related in structures that have been conserved in evolution. Each RNA polymerase is an enzyme complex composed of two large subunits that are homologous to the two largest subunits of prokaryotic RNA polymerases and are associated with smaller polypeptides, some of which are common to two or to all three eukaryotic enzymes. This remarkable conservation of structure most probably underlies a conservation of function and emphasizes the likelihood that information gained from the study of RNA polymerases from one organism will be applicable to others. The recent isolation of many mutations affecting the structure and/or function of eukaryotic and prokaryotic RNA polymerases now makes it feasible to begin integrating genetic and biochemical information from various species in order to develop a picture of these enzymes. The picture of eukaryotic RNA polymerases depicted in this article emphasizes the role(s) of different polypeptide regions in interaction with other subunits, cofactors, substrates, inhibitors, or accessory transcription factors, as well as the requirement for these interactions in transcription initiation, elongation, pausing, termination, and/or enzyme assembly. Most mutations described here have been isolated in eukaryotic organisms that have well-developed experimental genetic systems as well as amenable biochemistry, such as Saccharomyces cerevisiae, Drosophila melanogaster, and Caenorhabditis elegans. When relevant, mutations affecting regions of Escherichia coli RNA polymerase that are conserved among eukaryotes and prokaryotes are also presented. In addition to providing information about the structure and function of eukaryotic RNA polymerases, the study of mutations and of the pleiotropic phenotypes they imposed has underscored the central role played by these enzymes in many fundamental processes such as development and cellular differentiation.
真核生物中核编码基因的转录由三种不同的RNA聚合酶完成，分别称为聚合酶I、II和III，每种都是由10多个亚基组成的复合酶。从多种生物体中分离出编码真核生物RNA聚合酶亚基的基因，证实了先前的生化和免疫学数据，表明这三种酶在进化中保守的结构上密切相关。每种RNA聚合酶都是一种酶复合物，由两个与原核生物RNA聚合酶的两个最大亚基同源的大亚基组成，并与较小的多肽相关联，其中一些多肽是两种或所有三种真核酶共有的。这种显著的结构保守性很可能是功能保守的基础，并强调了从对一种生物体的RNA聚合酶研究中获得的信息适用于其他生物体的可能性。最近分离出许多影响真核和原核RNA聚合酶结构和/或功能的突变，现在使得开始整合来自不同物种的遗传和生化信息以构建这些酶的全貌成为可能。本文描绘的真核生物RNA聚合酶全貌强调了不同多肽区域在与其他亚基、辅因子、底物、抑制剂或辅助转录因子相互作用中的作用，以及这些相互作用在转录起始、延伸、暂停、终止和/或酶组装中的必要性。这里描述的大多数突变是在具有完善的实验遗传系统以及合适的生物化学条件的真核生物中分离出来的，如酿酒酵母、黑腹果蝇和秀丽隐杆线虫。在相关情况下，还介绍了影响大肠杆菌RNA聚合酶中真核生物和原核生物保守区域的突变。除了提供有关真核生物RNA聚合酶结构和功能的信息外，对突变及其所导致的多效性表型的研究强调了这些酶在许多基本过程如发育和细胞分化中所起的核心作用。
