Binding of the σ70 protein to the core subunits of Escherichia coli RNA polymerase, studied by iron-EDTA protein footprinting

Douglas P. Greiner, Karin A. Hughes, Angelo H. Gunasekera, Claude F. Meares

Research output: Contribution to journalArticle

65 Scopus citations


We have used a nonspecific protein cleaving reagent to map the interactions between subunits of the multisubunit enzyme RNA polymerase (Escherichia coli). We developed suitable conditions for using an untethered Fe-EDTA reagent, which does not bind significantly to proteins. Comparison of the cleaved fragments of the subunits from the core enzyme (α2ββ′) and the holoenzyme (core + σ70) shows that absence of the σ70 subunit is associated with the appearance of several cleavage sites on the subunits β (within 10 residues of sequence positions 745, 764, 795, and 812) and β′ (within 10 residues of sequence positions 581, 613, and 728). A cleavage site near β residue 604 is present in the holoenzyme but absent in the core, demonstrating that a conformational change occurs when σ70 binds. No differences are observed for the α subunit.

Original languageEnglish (US)
Pages (from-to)71-75
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - Jan 9 1996


ASJC Scopus subject areas

  • General
  • Genetics

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