Supercoiling Induced by Transcription

摘要: The biological implications of supercoiling by transcription are potentially significant (Pruss and Drlica 1989; Lilley Higgins 1991), a fundamental question is the extent to which determines level DNA in vivo. Transcription can induce template virtue topological relationship between elongating RNA polymerase (Liu Wang 1987). In some models, elongation requires that follows helical screw such there one 360° rotation enzyme for each 10.5 bp transcribed (Gamper Hearst 1982). Since elongates at rate about 40 nucleotides/s, an efficiently anchored complex should introduce approximately four negative super-turns upstream positive superturns downstream from actively expressed gene second. This would suggest extraordinarily fast rates localized after onset transcription. goal this chapter summarize examine our understanding kinetics mechanisms induced relate these insights mechanics elongation.