EMD-1568
E.coli core RNA polymerase
EMD-1568
Single-particle23.0 Å
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Map released: 01/04/2009
Last modified: 24/10/2012
Sample Organism:
Escherichia coli
Sample: Complex of E.coli RNA polymerase and Sigma 54
Deposition Authors: Bose D
,
Pape T
,
Burrows PC,
Rappas M,
Wigneshweraraj SR
,
Buck M,
Zhang X
Sample: Complex of E.coli RNA polymerase and Sigma 54
Deposition Authors: Bose D
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Organization of an activator-bound RNA polymerase holoenzyme.
Bose D
,
Pape T
,
Burrows PC,
Rappas M,
Wigneshweraraj SR
,
Buck M,
Zhang X
(2008) Mol. Cell , 32 , 337 - 346
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(2008) Mol. Cell , 32 , 337 - 346
Abstract:
Transcription initiation involves the conversion from closed promoter complexes, comprising RNA polymerase (RNAP) and double-stranded promoter DNA, to open complexes, in which the enzyme is able to access the DNA template in a single-stranded form. The complex between bacterial RNAP and its major variant sigma factor sigma(54) remains as a closed complex until ATP hydrolysis-dependent remodeling by activator proteins occurs. This remodeling facilitates DNA melting and allows the transition to the open complex. Here we present cryoelectron microscopy reconstructions of bacterial RNAP in complex with sigma(54) alone, and of RNAP-sigma(54) with an AAA+ activator. Together with photo-crosslinking data that establish the location of promoter DNA within the complexes, we explain why the RNAP-sigma(54) closed complex is unable to access the DNA template and propose how the structural changes induced by activator binding can initiate conformational changes that ultimately result in formation of the open complex.
Transcription initiation involves the conversion from closed promoter complexes, comprising RNA polymerase (RNAP) and double-stranded promoter DNA, to open complexes, in which the enzyme is able to access the DNA template in a single-stranded form. The complex between bacterial RNAP and its major variant sigma factor sigma(54) remains as a closed complex until ATP hydrolysis-dependent remodeling by activator proteins occurs. This remodeling facilitates DNA melting and allows the transition to the open complex. Here we present cryoelectron microscopy reconstructions of bacterial RNAP in complex with sigma(54) alone, and of RNAP-sigma(54) with an AAA+ activator. Together with photo-crosslinking data that establish the location of promoter DNA within the complexes, we explain why the RNAP-sigma(54) closed complex is unable to access the DNA template and propose how the structural changes induced by activator binding can initiate conformational changes that ultimately result in formation of the open complex.