COUPLING BETWEEN TRANSCRIPTION TERMINATION AND RNA-POLYMERASE INCHWORMING

Advancement of RNA polymerase of E. coil occurs in alternating laps of monotonic and inchworm-like movement. Cycles of inchworming are encod ed in DNA and involve straining and relaxation of the ternary complex accompanied by characteristic leaping of DNA and RNA footprints. We de monstrate that the oligo(T) tract that constitutes a normal part of tr anscription terminators acts as an inchworming signal so that the leap coincides with the termination event. Prevention of leaping with a ro adblock of cleavage-defective EcoRI protein results in suppression of RNA chain release at a termination site. The results indicate that str aining and relaxation of RNA polymerase are steps in the termination m echanism.