Transcription Termination: Variations on Common Themes

Transcription initiates pervasively in all organisms, which challenges the notion that the information to be expressed is selected mainly based on mechanisms defining where and when transcription is started. Together with post-transcriptional events, termination of transcription is essential for sorting out the functional RNAs from a plethora of transcriptional products that seemingly have no use in the cell. But terminating transcription is not that easy, given the high robustness of the elongation process. We review here many of the strategies that prokaryotic and eukaryotic cells have adopted to dismantle the elongation complex in a timely and efficient manner. We highlight similarities and diversity, underlying the existence of common principles in a diverse set of functionally convergent solutions.

TrendsTranscription termination is essential for many aspects of gene expression: often defining the limits of transcription units, dictating the fate of the RNA produced and limiting the extent of noncoding and pervasive transcription.The TEC is a stable macromolecular assembly that must ensure robust synthesis of sometimes long RNA molecules. Disassembling a TEC is an energy-requiring process that depends on the timely and precise action of machineries that can be as complex as the ones involved in its assembly.Mechanisms of transcription termination are generally specific for every RNA polymerase, but many similarities exist between these mechanisms that sometimes transcend evolutionary distances and reflect common thermodynamic principles underlying the process.