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

2019 ◽  
Author(s):  
Alexis Jaramillo Cartagena ◽  
Amy B. Banta ◽  
Nikhil Sathyan ◽  
Wilma Ross ◽  
Richard L. Gourse ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transcription Factor ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Structural Basis ◽  
Structural Element ◽  
Cryo Electron Microscopy ◽  
Promoter Dna ◽  
Transcription Activators

AbstractIn 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 (σS), the structure, along with p-benzoylphenylalanine crosslinking, reveals that Crl interacts with a structural element of the RNAP β’ subunit 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 σS and the β’CT. We propose that Crl, and other transcription activators that may use similar mechanisms, be designated σ-activators.Significance StatementIn bacteria, multiple σ factors can bind to a common core RNA polymerase (RNAP) to alter global transcriptional programs in response to environmental stresses. Many γ-proteobacteria, including the pathogens Yersinia pestis, Vibrio cholera, Escherichia coli, and Salmonella typhimurium, encode Crl, a transcription factor that activates σS-dependent genes. Many of these genes are involved in processes important for infection, such as biofilm formation. We determined a high-resolution cryo-electron microscopy structure of a Crl-σS-RNAP transcription initiation complex. The structure, combined with biochemical experiments, shows that Crl stabilizes σS-RNAP by tethering σS directly to the RNAP.

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.

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 Structural basis of transcription-translation coupling

Science ◽  
2020 ◽  
Vol 369 (6509) ◽  
pp. 1359-1365 ◽  
Author(s):  
Chengyuan Wang ◽  
Vadim Molodtsov ◽  
Emre Firlar ◽  
Jason T. Kaelber ◽  
Gregor Blaha ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Transcription Factors ◽  
Rna Polymerase ◽  
Active Center ◽  
Messenger Rna ◽  
Coupled Processes ◽  
Structural Basis ◽  
Cryo Electron Microscopy ◽  
Translation Coupling

In bacteria, transcription and translation are coupled processes in which the movement of RNA polymerase (RNAP)–synthesizing messenger RNA (mRNA) is coordinated with the movement of the first ribosome-translating mRNA. Coupling is modulated by the transcription factors NusG (which is thought to bridge RNAP and the ribosome) and NusA. Here, we report cryo–electron microscopy structures of Escherichia coli transcription-translation complexes (TTCs) containing different-length mRNA spacers between RNAP and the ribosome active-center P site. Structures of TTCs containing short spacers show a state incompatible with NusG bridging and NusA binding (TTC-A, previously termed “expressome”). Structures of TTCs containing longer spacers reveal a new state compatible with NusG bridging and NusA binding (TTC-B) and reveal how NusG bridges and NusA binds. We propose that TTC-B mediates NusG- and NusA-dependent transcription-translation coupling.

scholarly journals Effects of distortions by A-tracts of promoter B-DNA spacer region on the kinetics of open complex formation by Escherichia coli RNA polymerase.

2003 ◽  
Vol 50 (4) ◽  
pp. 909-920 ◽  
Author(s):  
Iwona K Kolasa ◽  
Tomasz Łoziński ◽  
Kazimierz L Wierzchowski
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Specific Interaction ◽  
Structural Data ◽  
Structural Morphology ◽  
Promoter Dna ◽  
Sigma Subunit ◽  
Kinetics Of

A-tracts in DNA due to their structural morphology distinctly different from the canonical B-DNA form play an important role in specific recognition of bacterial upstream promoter elements by the carboxyl terminal domain of RNA polymerase alpha subunit and, in turn, in the process of transcription initiation. They are only rarely found in the spacer promoter regions separating the -35 and -10 recognition hexamers. At present, the nature of the protein-DNA contacts formed between RNA polymerase and promoter DNA in transcription initiation can only be inferred from low resolution structural data and mutational and crosslinking experiments. To probe these contacts further, we constructed derivatives of a model Pa promoter bearing in the spacer region one or two An (n = 5 or 6) tracts, in phase with the DNA helical repeat, and studied the effects of thereby induced perturbation of promoter DNA structure on the kinetics of open complex (RPo) formation in vitro by Escherichia coli RNA polymerase. We found that the overall second-order rate constant ka of RPo formation, relative to that at the control promoter, was strongly reduced by one to two orders of magnitude only when the A-tracts were located in the nontemplate strand. A particularly strong 30-fold down effect on ka was exerted by nontemplate A-tracts in the -10 extended promoter region, where an involvement of nontemplate TG (-14, -15) sequence in a specific interaction with region 3 of sigma-subunit is postulated. A-tracts in the latter location caused also 3-fold slower isomerization of the first closed transcription complex into the intermediate one that precedes formation of RPo, and led to two-fold faster dissociation of the latter. All these findings are discussed in relation to recent structural and kinetic models of RPo formation.

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 The organization of open complexes between Escherichia coli RNA polymerase and DNA fragments carrying promoters either with or without consensus −35 region sequences

1990 ◽  
Vol 270 (1) ◽  
pp. 141-148 ◽  
Author(s):  
B Chan ◽  
A Spassky ◽  
S Busby
Keyword(s):  
Escherichia Coli ◽  
Complex Formation ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Point Mutations ◽  
Dna Fragments ◽  
Transcription Start ◽  
Footprint Analysis ◽  
Open Complex Formation ◽  
Promoter Dna

Transcription initiation at the Escherichia coli galP1 promoter does not depend on specific nucleotide sequences in the -35 region. Footprint analysis of transcriptionally competent complexes between E. coli RNA polymerase and DNA fragments carrying galP1 shows that RNA polymerase protects sequences as far upstream as -55, whereas sequences around the -35 region are exposed. In contrast, with galP1 derivatives carrying -35 region sequences resembling the consensus, RNA polymerase protects bases as far as -45, and the -35 region is fully protected. Taken together, our data suggest that the overall architecture of RNA polymerase-promoter complexes can vary according to whether or not consensus -35 region sequences are present; in the absence of these sequences, open complex formation requires distortion of the promoter DNA. However, the unwinding of promoter DNA around the transcription start is not affected by the nature of the -35 region sequence. With a galP1 derivative carrying point mutations in the spacer region that greatly reduce promoter activity, the protection of bases by RNA polymerase around the -10 sequence and transcription start site is reduced. In contrast, protection of the region upstream of -25 is unaffected by the spacer mutations, although sequences from -46 to -54 become hypersensitive to attack by potassium permanganate, indicating severe distortion or kinking of this zone. We suggest that, with this galP1 derivative, RNA polymerase is blocked in a complex that is an intermediate on the path to open complex formation.

scholarly journals Structural Basis of ECF-σ-Factor-Dependent Transcription Initiation

2018 ◽  
Author(s):  
Wei Lin ◽  
Sukhendu Mandal ◽  
David Degen ◽  
Min Sung Cho ◽  
Yu Feng ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Crystal Structures ◽  
Transcription Initiation ◽  
Structural Basis ◽  
Functional Modules ◽  
Dna Interactions ◽  
Protein Dna Interactions ◽  
Σ Factor ◽  
Promoter Dna

SUMMARYExtracytoplasmic (ECF) σ factors, the largest class of alternative σ factors, are related to primary σ factors, but have simpler structures, comprising only two of the six conserved functional modules present in primary σ factors: region 2 (σR2) and region 4 (σR4). Here, we report crystal structures of transcription initiation complexes containing Mycobacterium tuberculosis RNA polymerase (RNAP), M. tuberculosis ECF σ factor σL, and promoter DNA. The structures show that σR2 and σR4 of the ECF σ factor occupy the same sites on RNAP as in primary σ factors, show that the connector between σR2 and σR4 of the ECF σ factor--although unrelated in sequence--follows the same path through RNAP as in primary σ factors, and show that the ECF σ factor uses the same strategy to bind and unwind promoter DNA as primary σ factors. The results define protein-protein and protein-DNA interactions involved in ECF-σ-factor-dependent transcription initiation.

scholarly journals Structural basis of the nucleosome transition during RNA polymerase II passage

Science ◽  
2018 ◽  
Vol 362 (6414) ◽  
pp. 595-598 ◽  
Author(s):  
Tomoya Kujirai ◽  
Haruhiko Ehara ◽  
Yuka Fujino ◽  
Mikako Shirouzu ◽  
Shun-ichi Sekine ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Genomic Dna ◽  
Structural Basis ◽  
Histone Octamer ◽  
Contact Sites ◽  
Cryo Electron Microscopy ◽  
Nucleosomal Dna ◽  
Foreign Dna

Genomic DNA forms chromatin, in which the nucleosome is the repeating unit. The mechanism by which RNA polymerase II (RNAPII) transcribes the nucleosomal DNA remains unclear. Here we report the cryo–electron microscopy structures of RNAPII-nucleosome complexes in which RNAPII pauses at the superhelical locations SHL(−6), SHL(−5), SHL(−2), and SHL(−1) of the nucleosome. RNAPII pauses at the major histone-DNA contact sites, and the nucleosome interactions with the RNAPII subunits stabilize the pause. These structures reveal snapshots of nucleosomal transcription, in which RNAPII gradually tears DNA from the histone surface while preserving the histone octamer. The nucleosomes in the SHL(−1) complexes are bound to a “foreign” DNA segment, which might explain the histone transfer mechanism. These results provide the foundations for understanding chromatin transcription and epigenetic regulation.

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

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
James Chen ◽  
Saumya Gopalkrishnan ◽  
Courtney Chiu ◽  
Albert Y Chen ◽  
Elizabeth A Campbell ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Conformational Changes ◽  
Transcription Initiation ◽  
Structural Changes ◽  
Structural Basis ◽  
E Coli ◽  
Bacterial Proteins ◽  
Promoter Complex ◽  
Promoter Dna ◽  
Induced Changes

TraR 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, but the structural basis for regulation by these factors remains 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 revealed TraR-induced changes in RNAP conformational heterogeneity. 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 complex disruption by the Mfd translocase

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jin Young Kang ◽  
Eliza Llewellyn ◽  
James Chen ◽  
Paul Dominic B Olinares ◽  
Joshua Brewer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Nucleotide Excision Repair ◽  
Bound States ◽  
Excision Repair ◽  
Structural Basis ◽  
Template Strand ◽  
Cryo Electron Microscopy ◽  
Nucleotide Excision ◽  
Transcription Coupled Repair

Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) that preferentially removes lesions from the template-strand (t-strand) that stall RNA polymerase (RNAP) elongation complexes (ECs). Mfd mediates TCR in bacteria by removing the stalled RNAP concealing the lesion and recruiting Uvr(A)BC. We used cryo-electron microscopy to visualize Mfd engaging with a stalled EC and attempting to dislodge the RNAP. We visualized seven distinct Mfd-EC complexes in both ATP and ADP-bound states. The structures explain how Mfd is remodeled from its repressed conformation, how the UvrA-interacting surface of Mfd is hidden during most of the remodeling process to prevent premature engagement with the NER pathway, how Mfd alters the RNAP conformation to facilitate disassembly, and how Mfd forms a processive translocation complex after dislodging the RNAP. Our results reveal an elaborate mechanism for how Mfd kinetically discriminates paused from stalled ECs and disassembles stalled ECs to initiate TCR.

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