Fig. 3: Repetitive transcription on templates with two adjacent promoters.
From: Force and the α-C-terminal domains bias RNA polymerase recycling
a In a recording for a template with converging promoters, after one transcription event from P1 under assisting force, RNAP slid to P2 and completed three cycles of transcription opposing force before finally dissociating from the promoter. b A time-based catalog of the transcription events involving promoter P2 observed along the templates with converging promoters shows the beginning and end of each transcription event with different rounds depicted in different colors. Transcription from P1, the promoter oriented in the direction of force, never repeated. c In a recording for a template with diverging promoters, transcription from P1, opposing the direction of force, repeated four times before RNAP slid past P1 to re-initiate once from P2 assisted by force. d A time-based catalog of the transcription events involving promoter P2 for templates with diverging promoters shows repetitive events from promoter P1, oriented against the force but only single primary or final repetitive events from P2 oriented with the force. e In figures prepared with Chimera version 1.2, α-CTDs are shown to interact with promoter DNA in a closed rrnB promoter complex22 (left). An enlarged view of the α-CTD shows contacts with the UP element (right). f Deletion of α-CTD diminished the probability that RNAP turned around to re-initiate in the direction opposite to the primary transcription event (anti-sense re-initiation) on templates with converging or diverging promoters.
