TRANSLOCATION OF THE ESCHERICHIA-COLI TRANSCRIPTION COMPLEX OBSERVED IN THE REGISTER-11 TO REGISTER-20 - JUMPING OF RNA-POLYMERASE AND ASYMMETRIC EXPANSION AND CONTRACTION OF THE TRANSCRIPTION-BUBBLE

Translocation of DNA-dependent RNA polymerase along the DNA template d uring RNA synthesis encompasses continuous as well as discontinuous st eps, This is demonstrated by chemical probing of transcription complex es stalled in consecutive registers of RNA synthesis at base positions +11, +12, +14, +16, +18, and +20, The ''transcription bubble'' transl ocates by continuous opening of the downstream edge in tandem with the growing RNA chain and discontinuous closing at the upstream edge afte r at least nine steps of RNA synthesis, The position of the enzyme rem ains unchanged during extension of the transcription bubble and ''jump s'' 10 bp downstream simultaneously with collapse of the transcription bubble.