Preface

RNA polymerases (RNAPs) are essential to all life forms and responsible for the regulated and template DNA-dependent transcription of all genetic information. A plethora of basal and gene-specific transcription factors interact physically and functionally with RNAP, which results in the execution of a highly fine-tuned genetic program that is at the very heart of biology. RNAPs come in a range of flavors, but notably all RNAPs responsible for the transcription of cellular genomes are evolutionary related and are thus derived from one common ancestor. Recent technological advances have given us unprecedented insights into the function and mechanisms of RNAPs. This book chapter serves to describe our modern understanding of the structure, function, and evolution of RNAPs in the three principal domains of life: the Bacteria, Archaea, and Eukarya.

Transcription in the informationprocessing circuitry of life

Since Francis Crick phrased the “central dogma” of molecular biology in the mid-1950s – according to which DNA-makes-RNA-makes-protein – scientists from a broad range of backgrounds have investigated the flow of genetic information in biological systems (Watson and Crick, 1953). According to this traditional view, the DNA template-dependent synthesis of DNA is referred to as replication, the DNA template-dependent synthesis of RNA is transcription, and RNA in turn is translated into proteins (Figure 5.1). Soon after the discovery that nucleic acids not only encode the genetic information, but are also instrumental in translating it into proteins in the form of ribosomes (e.g., rRNA) and their ligands (e.g., tRNA), it became apparent that this assumed unidirectional flow of information is anything but simple, nor is it unidirectional (Figure 5.1).