1 H n.m.r. of the DNA-dependent RNA polymerase from Escherichia coli (original) (raw)
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A general view: Structure and function of the subunits of E. coli RNA polymerase
Journal of Cell and Molecular Biology, 2003
The DNA-dependent RNA polymerases are widespread throughout nature. E. coli RNA polymerase, one of the most well characterized polymerase, consists of two major forms, core enzyme with subunit stoichiometry of α 2 ββ' and holoenzyme which contains an additional σ subunit to core enzyme. E. coli RNA polymerase plays a central role in transcription. While the core enzyme catalyses the elongation and termination of transcription, to initiate core enzyme needs to combine with σ subunit. The three dimensional structure of this multimeric enzyme revealed a thumb-like projection. Using the electron microscope, Tichelar and Heel (1990) proposed a model that is in agreement with both β and β' together constituting a V-like structure and α dimer associates at the short ends, while σ is positioned within the concave side of the core, next to the dimer. In this review, the structure and related functions of the subunits of E. coli DNA-dependent RNA polymerase is presented based on several researches and reviews. Considering biochemical and genetic studies on the RNA polymerase of E. coli, a genetic walk on the subunits is summarized.
Escherichia coli RNA polymerase core and holoenzyme structures
The EMBO Journal, 2000
Multisubunit RNA polymerase is an essential enzyme for regulated gene expression. Here we report two Escherichia coli RNA polymerase structures: an 11.0 A Ê structure of the core RNA polymerase and a 9.5 A Ê structure of the s 70 holoenzyme. Both structures were obtained by cryo-electron microscopy and angular reconstitution. Core RNA polymerase exists in an open conformation. Extensive conformational changes occur between the core and the holoenzyme forms of the RNA polymerase, which are largely associated with movements in b¢. All common RNA polymerase subunits (a 2 , b, b¢) could be localized in both structures, thus suggesting the position of s 70 in the holoenzyme.
RNA polymerase holoenzyme: structure, function and biological implications
Current Opinion in Microbiology, 2003
The past three years have marked the breakthrough in our understanding of the structural and functional organization of RNA polymerase. The latest major advance was the highresolution structures of bacterial RNA polymerase holoenzyme and the holoenzyme in complex with promoter DNA. Together with an array of genetic, biochemical and biophysical data accumulated to date, the structures provide a comprehensive view of dynamic interactions between the major components of transcription machinery during the early stages of the transcription cycle. They include the binding of sigma factor to the core enzyme, and the recognition of promoter sequences and DNA melting by holoenzyme, transcription initiation and promoter clearance.
Cell, 2002
to this multistep process: bacterial RNAP core enzyme (Zhang et al., 1999; subunit composition Ј//␣ I /␣ II /), eukaryotic RNAP II core enzyme ⌬4/7 (Cramer et al., 2001; subunit composition 1/2/3/5/6/8/9/10/11/12, where 1, 2, 3, 11, and 6 are homologs of bacterial RNAP and ; Ebright, 2000), and a eukaryotic RNAP II tailed-template elongation complex .
Biochemistry, 1987
The interaction of the Escherichia coli R N A polymerase with several forms of D N A has been studied by difference absorption spectroscopy, protection against endonuclease$and limited, specific initiation. The core enzyme is able to open duplex poly[d(A-T)] in 10 m M KCl. The core enzyme binds to promoters in linear D N A in a salt-dependent manner, but it does not bind to the same promoters in supercoiled DNA. The binding of the core enzyme is not as tight as that of the holoenzyme. The holoenzyme initiates specific transcription from promoters in a salt-dependent manner. The core enzyme also initiates specific transcription from the same promoters at approximately one-fifth the level of the holoenzyme with a different salt dependence. The profile of the salt dependence of specific transcription initiation varies with the promoter. The origin of differences between holoenzyme-DNA and core enzymeDNA interactions and the mechanism whereby u improves transcriptional specificity are discussed in light of these data. 'This research was supported in part by US. Public Health Service Grant GM-23697. From a thesis submitted by A.R.W. to the academic faculty of Colorado State University in partial fulfillment of the requirements for the degree of Ph.D.
Crystal structure of a bacterial RNA polymerase holoenzyme at 2.6 � resolution
Acta Crystallogr a, 2002
In bacteria, the binding of a single protein, the initiation factor σ, to a multi-subunit RNA polymerase core enzyme results in the formation of a holoenzyme, the active form of RNA polymerase essential for transcription initiation. Here we report the crystal structure of a bacterial RNA polymerase holoenzyme from Thermus thermophilus at 2.6Å resolution. In the structure, two amino-terminal domains of the σ subunit form a V-shaped structure near the opening of the upstream DNA-binding channel of the active site cleft. The carboxy-terminal domain of σ is near the outlet of the RNA-exit channel, about 57Å from the N-terminal domains. The extended linker domain forms a hairpin protruding into the active site cleft, then stretching through the RNA-exit channel to connect the N- and C-terminal domains. The holoenzyme structure provides insight into the structural organization of transcription intermediate complexes and into the mechanism of transcription initiation.