Identification of a component separated on Mono Q purification of Escherichia coli RNA polymerase as an NTPase

AbstractStandard preparations of Escherichia coli RNA polymerase (RNAP) contain NTPase activity. High-performance anion exchange chromatography on Mono Q has recently been used by Hager et al. [1990, Biochemistry 29, 7890–7894] to fractionate RNAP into holoenzyme (α,ββ′σ) and core (α,ββ′) forms, plus other protein components. We found that one of these components, of protomer size slightly larger than the σ70 subunit, has NTPase activity; it is efficiently separated on Mono Q, leaving transcriptionally active holoenzyme and core apparently free of NTPase activity. Because of the similarity in size with σ70, the NTPase component may escape detection by routine gel electrophoresis