Factor-dependent archaeal transcription termination

Significance Proper transcription regulation is necessary for timely and accurate gene expression underlying growth and development. Transcription is regulated at each stage of the transcription cycle—initiation, elongation, and termination—and it is critical to define the factors and sequences regulating RNA polymerase activity. Many studies have investigated the mechanisms used by transcription factors involved in regulation of transcription initiation and elongation, but a mechanistic understanding of transcription termination has been slower to emerge. Here we characterize the first archaeal transcription termination factor, termed euryarchaeal termination activity (Eta). The mechanisms of Eta-mediated termination provide the first understanding of archaeal factor-dependent termination and provide insight into and contrast with the mechanisms used for factor-dependent termination in extant life.