Dissection of two hallmarks of the open promoter complex by mutation in an RNA polymerase core subunit

S. Nechaev, M. Chlenov, K. Severinov

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32 Citations (Scopus)

Abstract

Deletion of 10 evolutionarily conserved amino acids from the β subunit of Escherichia coli RNA polymerase leads to a mutant enzyme that is unable to efficiently hold onto DNA. Open promoter complexes formed by the mutant enzyme are in rapid equilibrium with closed complexes and, unlike the wild-type complexes, are highly sensitive to the DNA competitor heparin (Martin, E., Sagitov, V., Burova, E., Nikiforov, V., and Goldfarb, A. (1992) J. Biol. Chem. 267, 20175-20180). Here we show that despite this instability, the mutant enzyme forms partially open complexes at temperatures as low as 0 °C when the wild-type complex is fully closed. Thus, the two hallmarks of the open promoter complex, the stability toward a challenge with DNA competitors and the sensitivity toward low temperature, can be uncoupled by mutation and may be independent in the wild-type complex. We use the high resolution structure of Thermus aquaticus RNA polymerase core to build a functional model of promoter complex formation that accounts for the observed defects of the E. coli RNA polymerase mutants.

Original languageEnglish
Pages (from-to)25516-25522
Number of pages7
JournalJournal of Biological Chemistry
Volume275
Issue number33
DOIs
Publication statusPublished - 18 Aug 2000
Externally publishedYes

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