Contact: Joseph Blumberg
Caption: Initial transcription by RNA polymerase proceeds through a "DNA scrunching" mechanism, in which the enzyme remains stationary on promoter DNA and pulls into itself downstream DNA. [Proposed movements of the template and nontemplate DNA strands are indicated by blue outlined and red-outlined arrows. Proposed positions at which the scrunched template and nontemplate DNA strands emerge from the enzyme are indicated by orange and pink dashed lines. Positions of fluorescent probes used to analyze scrunching are indicated in green (donor probe on polymerase), brick red (acceptor probe at promoter position +20 in absence of scrunching), and bright red (acceptor probe at promoter position +20 in presence of scrunching).]
Credit: Image provided by Achillefs Kapanidis, Shimon Weiss, and Richard H. Ebright.
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