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Boudvillain, M ; Schwartz, A ; Rahmouni, R

Limited topological alteration of the T7 RNA polymerase active-center at intrinsic termination sites

Biochemistry 41 3137-3146

par Administrateur - publié le

Abstract :

Transcription terminators trigger the dissociation of RNA polymerase elongation complexes and the release of RNA products at specific DNA template positions. The mechanism by which these signals alter the catalytic properties of the highly processive elongation transcription complexes is unclear. Here, we propose that intrinsic terminators impede transcript elongation by promoting a misarrangement of reactants and catalytic effectors within the active site of T7 RNA polymerase. In effect, a productive catalytic coordination network can be readily restored when Mg(2+) effectors are replaced by the more "relaxing" Mn(2+) ions, leading to transcript elongation beyond the termination point.