The evolving story of the omega subunit of bacterial RNA polymerase

Omega (ω) is the smallest subunit of bacterial RNA polymerase (RNAP). Although identified early in RNAP research, its function remained ambiguous and shrouded by controversy for a considerable period. It has subsequently been shown that the protein has a structural role in maintenance of the conformation of the largest subunit, β′, and recruitment of β′ to the enzyme assembly. Conservation of this function across all forms of life indicates the importance of its role. Several recent observations have suggested additional functional roles for this protein and have settled some long-standing controversies surrounding it. In this context, revisiting the ω subunit story is especially interesting; here, we review the progress of ω research since its discovery and highlight the importance of these recent observations.