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Wrapping of DNA around the E.coli RNA polymerase open promoter complex
Author(s) -
Rivetti Claudio,
Guthold Martin,
Bustamante Carlos
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.16.4464
Subject(s) - biology , rna polymerase , polymerase , microbiology and biotechnology , dna , genetics , rna , gene
High‐resolution atomic force microscopy (AFM) and biochemical methods were used to analyze the structure of Escherichia coli RNA polymerase·σ 70 (RNAP) open promoter complex (RP o ). A detailed analysis of a large number of molecules shows that the DNA contour length of RP o is reduced by ∼30 nm (∼90 bp) relative to the free DNA. The DNA bend angle measured with different methods varied from 55 to 88°. The contour length reduction and the DNA bend angle were much less in inactive RNAP–DNA complexes. These results, together with previously published observations, strongly support the notion that during transcription initiation, the promoter DNA wraps nearly 300° around the polymerase. This amount of DNA bending requires an energy of 60 kJ/mol. The structural analysis of the open promoter complexes revealed that two‐thirds of the DNA wrapped around the RNAP is part of a region upstream of the transcription start site, whereas the remaining one‐third is part of the downstream region. Based on these data, a model of the σ 70 ·RP o conformation is proposed.