Heterogeneity of RNA polymerase in Escherichia coli. I. A new holoenzyme containing a new sigma factor

Ryuji Fukuda, Yoichiro Iwakura, Akira Ishihama

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)

Abstract

In addition to the holoenzyme with the subunit structure α2ββ′σ, small quantities of a new form of the DNA-dependent RNA polymerase holoenzyme with similar template specificity but distinct structure were found in Escherichia coli; this enzyme (holoenzyme II), separated from the standard polymerase (holoenzyme I) to apparent homogeneity by column chromatography on DNA-cellulose, was composed of the core enzyme subunit and a 56,000 molecular weight polypeptide, designated as σ′ subunit, which exhibited multiple functions, the same functions so far observed for the σ subunit, i.e. stimulation of transcription on certain DNA templates, and reconstitution of active polymerase. Since no structural relatedness, however, was found for the two subunits, σ and σ′, they may be distinct species of initiation factor; heterogeneity of the RNA polymerase holoenzyme was therefore suggested, with each form containing the common core unit and one of the two different species of the initiation factor.

Original languageEnglish
Pages (from-to)353-360,IN7-IN8,361-367
JournalJournal of Molecular Biology
Volume83
Issue number3
DOIs
Publication statusPublished - 5 Mar 1974

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