Bacterial RNA polymerase can retain sigma70 throughout transcription.

Harden TT, Wells CD, Friedman LJ, Landick R, Hochschild A, Kondev J, Gelles J
Proc Natl Acad Sci U S A. 2016 Jan 5. pii: 201513899. PubMed Article

Plasmids from Article

ID	Plasmid	Purpose
70061	pCDW114	artificial transcription template "wild-type"
70062	pCDW115	artificial transcription template "pause ablation"
70063	pTH07	artificial transcription template "distal pause"
70064	pTH09	artificial transcription template "terminator insertion"