Transcription Against an Applied Force

摘要: The force produced by a single molecule of Escherichia coli RNA polymerase during transcription was measured optically. Polymerase immobilized on surface used to transcribe DNA template attached polystyrene bead 0.5 micrometer in diameter. position interferometry while opposing translocation the along applied with an optical trap. At saturating nucleoside triphosphate concentrations, molecules stalled reversibly at mean estimated be 14 piconewtons. This is substantially larger than those for cytoskeletal motors kinesin and myosin exceeds mechanical loads that are oppose transcriptional elongation vivo. data consistent efficient conversion free energy liberated synthesis into work.