scholarly journals Structure of a bacterial RNA polymerase holoenzyme open promoter complex

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Brian Bae ◽  
Andrey Feklistov ◽  
Agnieszka Lass-Napiorkowska ◽  
Robert Landick ◽  
Seth A Darst
Keyword(s):  
Rna Polymerase ◽  
Bubble Formation ◽  
Thermus Aquaticus ◽  
Transcription Bubble ◽  
Template Strand ◽  
Bacterial Rna ◽  
Promoter Complex ◽  
Primary Means ◽  
Promoter Dna ◽  
Biochemical Analyses

Initiation of transcription is a primary means for controlling gene expression. In bacteria, the RNA polymerase (RNAP) holoenzyme binds and unwinds promoter DNA, forming the transcription bubble of the open promoter complex (RPo). We have determined crystal structures, refined to 4.14 Å-resolution, of RPo containing Thermus aquaticus RNAP holoenzyme and promoter DNA that includes the full transcription bubble. The structures, combined with biochemical analyses, reveal key features supporting the formation and maintenance of the double-strand/single-strand DNA junction at the upstream edge of the −10 element where bubble formation initiates. The results also reveal RNAP interactions with duplex DNA just upstream of the −10 element and potential protein/DNA interactions that direct the DNA template strand into the RNAP active site. Addition of an RNA primer to yield a 4 base-pair post-translocated RNA:DNA hybrid mimics an initially transcribing complex at the point where steric clash initiates abortive initiation and σA dissociation.

scholarly journals Structural origins of Escherichia coli RNA polymerase open promoter complex stability

2021 ◽  
Vol 118 (40) ◽  
pp. e2112877118
Author(s):  
Ruth M. Saecker ◽  
James Chen ◽  
Courtney E. Chiu ◽  
Brandon Malone ◽  
Johanna Sotiris ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
De Novo ◽  
Promoter Strength ◽  
Transcription Bubble ◽  
Template Strand ◽  
Solution Studies ◽  
Active Site Cleft ◽  
Promoter Dna

The first step in gene expression in all organisms requires opening the DNA duplex to expose one strand for templated RNA synthesis. In Escherichia coli, promoter DNA sequence fundamentally determines how fast the RNA polymerase (RNAP) forms “open” complexes (RPo), whether RPo persists for seconds or hours, and how quickly RNAP transitions from initiation to elongation. These rates control promoter strength in vivo, but their structural origins remain largely unknown. Here, we use cryoelectron microscopy to determine the structures of RPo formed de novo at three promoters with widely differing lifetimes at 37 °C: λPR (t1/2 ∼10 h), T7A1 (t1/2 ∼4 min), and a point mutant in λPR (λPR-5C) (t1/2 ∼2 h). Two distinct RPo conformers are populated at λPR, likely representing productive and unproductive forms of RPo observed in solution studies. We find that changes in the sequence and length of DNA in the transcription bubble just upstream of the start site (+1) globally alter the network of DNA–RNAP interactions, base stacking, and strand order in the single-stranded DNA of the transcription bubble; these differences propagate beyond the bubble to upstream and downstream DNA. After expanding the transcription bubble by one base (T7A1), the nontemplate strand “scrunches” inside the active site cleft; the template strand bulges outside the cleft at the upstream edge of the bubble. The structures illustrate how limited sequence changes trigger global alterations in the transcription bubble that modulate the RPo lifetime and affect the subsequent steps of the transcription cycle.

scholarly journals Structural origins of Escherichia coli RNA polymerase open promoter complex stability

2021 ◽  
Author(s):  
Ruth M. Saecker ◽  
James Chen ◽  
Courtney E. Chiu ◽  
Brandon Malone ◽  
Johanna Sotiris ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
De Novo ◽  
Promoter Strength ◽  
Transcription Bubble ◽  
Template Strand ◽  
Solution Studies ◽  
Active Site Cleft ◽  
Promoter Dna

AbstractThe first step of gene expression in all organisms requires opening the DNA duplex to expose one strand for templated RNA synthesis. In Escherichia coli, promoter DNA sequence fundamentally determines how fast the RNA polymerase (RNAP) forms “open” complexes (RPo), whether RPo persists for seconds or hours, and how quickly RNAP transitions from initiation to elongation. These rates control promoter strength in vivo but their structural origins remain largely unknown. Here we use cryo-electron microscopy to determine structures of RPo formed de novo at three promoters with widely differing lifetimes at 37°C: λPR (t1/2 ∼ 10 hours), T7A1 (t1/2 ∼ 4 minutes), and a point mutant in λPR (λPR-5C) (t1/2 ∼ 2 hours). Two distinct RPo conformers are populated at λPR, likely representing productive and unproductive forms of RPo observed in solution studies. We find that changes in the sequence and length of DNA in the transcription bubble just upstream of the start site (+1) globally alter the network of DNA-RNAP interactions, base stacking, and strand order in the single-stranded DNA of the transcription bubble; these differences propagate beyond the bubble to upstream and downstream DNA. After expanding the transcription bubble by one base (T7A1), the nontemplate-strand “scrunches” inside the active site cleft; the template-strand bulges outside the cleft at the upstream edge of the bubble. The structures illustrate how limited sequence changes trigger global alterations in the transcription bubble that modulate RPo lifetime and affect the subsequent steps of the transcription cycle.

scholarly journals Direct binding of TFEα opens DNA binding cleft of RNA polymerase

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung-Hoon Jun ◽  
Jaekyung Hyun ◽  
Jeong Seok Cha ◽  
Hoyoung Kim ◽  
Michael S. Bartlett ◽  
...  
Keyword(s):  
Dna Binding ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Structural Basis ◽  
Transcription Bubble ◽  
Cryo Electron Microscopy ◽  
Direct Binding ◽  
Binding Cleft ◽  
Promoter Dna ◽  
Winged Helix Domain

AbstractOpening of the DNA binding cleft of cellular RNA polymerase (RNAP) is necessary for transcription initiation but the underlying molecular mechanism is not known. Here, we report on the cryo-electron microscopy structures of the RNAP, RNAP-TFEα binary, and RNAP-TFEα-promoter DNA ternary complexes from archaea, Thermococcus kodakarensis (Tko). The structures reveal that TFEα bridges the RNAP clamp and stalk domains to open the DNA binding cleft. Positioning of promoter DNA into the cleft closes it while maintaining the TFEα interactions with the RNAP mobile modules. The structures and photo-crosslinking results also suggest that the conserved aromatic residue in the extended winged-helix domain of TFEα interacts with promoter DNA to stabilize the transcription bubble. This study provides a structural basis for the functions of TFEα and elucidates the mechanism by which the DNA binding cleft is opened during transcription initiation in the stalk-containing RNAPs, including archaeal and eukaryotic RNAPs.

scholarly journals E. coli TraR allosterically regulates transcription initiation by altering RNA polymerase conformation and dynamics

2019 ◽  
Author(s):  
James Chen ◽  
Saumya Gopalkrishnan ◽  
Courtney Chiu ◽  
Albert Y. Chen ◽  
Elizabeth A. Campbell ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Conformational Changes ◽  
Transcription Initiation ◽  
Structural Changes ◽  
E Coli ◽  
Bacterial Proteins ◽  
Cryo Electron Microscopy ◽  
Promoter Complex ◽  
Promoter Dna ◽  
Induced Changes

AbstractTraR and its homolog DksA are bacterial proteins that regulate transcription initiation by binding directly to RNA polymerase (RNAP) rather than to promoter DNA. Effects of TraR mimic the combined effects of DksA and its cofactor ppGpp. How TraR and its homologs regulate transcription is unclear. Here, we use cryo-electron microscopy to determine structures of Escherichia coli RNAP, with or without TraR, and of an RNAP-promoter complex. TraR binding induced RNAP conformational changes not seen in previous crystallographic analyses, and a quantitative analysis of RNAP conformational heterogeneity revealed TraR-induced changes in RNAP dynamics. These changes involve mobile regions of RNAP affecting promoter DNA interactions, including the βlobe, the clamp, the bridge helix, and several lineage-specific insertions. Using mutational approaches, we show that these structural changes, as well as effects on σ70 region 1.1, are critical for transcription activation or inhibition, depending on the kinetic features of regulated promoters.

scholarly journals Structural basis for transcription activation by Crl through tethering of σS and RNA polymerase

2019 ◽  
Vol 116 (38) ◽  
pp. 18923-18927 ◽  
Author(s):  
Alexis Jaramillo Cartagena ◽  
Amy B. Banta ◽  
Nikhil Sathyan ◽  
Wilma Ross ◽  
Richard L. Gourse ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Structural Basis ◽  
Functional Importance ◽  
Structural Element ◽  
Cryo Electron Microscopy ◽  
Promoter Complex ◽  
Σ Factor ◽  
Promoter Dna ◽  
Transcription Activators

In bacteria, a primary σ-factor associates with the core RNA polymerase (RNAP) to control most transcription initiation, while alternative σ-factors are used to coordinate expression of additional regulons in response to environmental conditions. Many alternative σ-factors are negatively regulated by anti–σ-factors. In Escherichia coli, Salmonella enterica, and many other γ-proteobacteria, the transcription factor Crl positively regulates the alternative σS-regulon by promoting the association of σS with RNAP without interacting with promoter DNA. The molecular mechanism for Crl activity is unknown. Here, we determined a single-particle cryo-electron microscopy structure of Crl-σS-RNAP in an open promoter complex with a σS-regulon promoter. In addition to previously predicted interactions between Crl and domain 2 of σS (σS2), the structure, along with p-benzoylphenylalanine cross-linking, reveals that Crl interacts with a structural element of the RNAP β′-subunit that we call the β′-clamp-toe (β′CT). Deletion of the β′CT decreases activation by Crl without affecting basal transcription, highlighting the functional importance of the Crl-β′CT interaction. We conclude that Crl activates σS-dependent transcription in part through stabilizing σS-RNAP by tethering σS2 and the β′CT. We propose that Crl, and other transcription activators that may use similar mechanisms, be designated σ-activators.

Investigations of the modular structure of bacterial promoters

2006 ◽  
Vol 73 ◽  
pp. 1-10 ◽  
Author(s):  
Nora S. Miroslavova ◽  
Stephen J.W. Busby
Keyword(s):  
Rna Polymerase ◽  
Dna Sequence ◽  
Transcription Initiation ◽  
Promoter Activity ◽  
Modular Structure ◽  
Bacterial Rna ◽  
Sequence Elements ◽  
Promoter Dna ◽  
Transcript Initiation ◽  
Rna Polymerase Holoenzyme

Bacterial RNA polymerase holoenzyme carries different determinants that contact different promoter DNA sequence elements. These contacts are essential for the recognition of promoters prior to transcript initiation. Here, we have investigated how active promoters can be built from different combinations of elements. Our results show that the contribution of different contacts to promoter activity is critically dependent on the overall promoter context, and that certain combinations of contacts can hinder transcription initiation.

6S RNA – an ancient regulator of bacterial RNA polymerase rediscovered

2005 ◽  
Vol 386 (12) ◽  
pp. 1273-1277 ◽  
Author(s):  
Dagmar K. Willkomm ◽  
Roland K. Hartmann
Keyword(s):  
Rna Polymerase ◽  
Dependent Manner ◽  
Bacterial Rna ◽  
Promoter Complex ◽  
6S Rna ◽  
Σ Factor ◽  
Central Bulge ◽  
The Common ◽  
Non Coding Rnas ◽  
Year 2000

AbstractThe bacterial riboregulator 6S RNA was one of the first non-coding RNAs to be discovered in the late 1960s, but its cellular role remained enigmatic until the year 2000. 6S RNA, only recognized to be ubiquitous among bacteria in 2005, binds to RNA polymerase in a σ factor-dependent manner to repress transcription from a subgroup of promoters. The common feature of a double-stranded rod with a central bulge has led to the proposal that 6S RNA may mimic an open promoter complex.

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