Studies on the ω subunit of Escherichia coli RNA polymerase: its role in the recovery of denatured enzyme activity

Abstract

Highly purified Escherichia coli RNA polymerase contains a small subunit termed ω that has a molecular mass of 10105 Da and is comprised of 91 amino acids. To elucidate the function of ω, whose role is as yet undefined, the subunit was purified to over 95% purity from an overproducing strain [BL21 (pGP1-2, pE3C-2)]. Purified ω was then reconstituted with RNA polymerase isolated from an ω-less mutant. Externally added ω inhibited promoter-specific transcriptional activity at all promoters tested. Renaturation of fully denatured ω-less RNA polymerase in the presence of excess ω yielded maximum recovery of activity suggesting a structural rather than functional role for ω.