scholarly journals Faculty Opinions recommendation of What is in the black box? The discovery of the sigma factor and the subunit structure of E. coli RNA polymerase.

2021 ◽  
Author(s):  
Victor Norris
Keyword(s):  
Rna Polymerase ◽  
Sigma Factor ◽  
Black Box ◽  
Subunit Structure ◽  
E Coli

scholarly journals Activity of Rhodobacter sphaeroides RpoHII, a Second Member of the Heat Shock Sigma Factor Family

2006 ◽  
Vol 188 (16) ◽  
pp. 5712-5721 ◽  
Author(s):  
Heather A. Green ◽  
Timothy J. Donohue
Keyword(s):  
Heat Shock ◽  
Rna Polymerase ◽  
Rhodobacter Sphaeroides ◽  
Sigma Factor ◽  
Distinct Group ◽  
Temperature Sensitive ◽  
Sequence Comparisons ◽  
E Coli ◽  
Primary Amino ◽  
Temperature Sensitive Phenotype

ABSTRACT We have identified a second RpoH homolog, RpoHII, in the α-proteobacterium Rhodobacter sphaeroides. Primary amino acid sequence comparisons demonstrate that R. sphaeroides RpoHII belongs to a phylogenetically distinct group with RpoH orthologs from α-proteobacteria that contain two rpoH genes. Like its previously identified paralog, RpoHI, RpoHII is able to complement the temperature-sensitive phenotype of an Escherichia coli σ32 (rpoH) mutant. In addition, we show that recombinant RpoHI and RpoHII each transcribe two E. coli σ32-dependent promoters (rpoD PHS and dnaK P1) when reconstituted with E. coli core RNA polymerase. We observed differences, however, in the ability of each sigma factor to recognize six R. sphaeroides promoters (cycA P1, groESL 1, rpoD PHS, dnaK P1, hslO, and ecfE), all of which resemble the E. coli σ32 promoter consensus. While RpoHI reconstituted with R. sphaeroides core RNA polymerase transcribed all six promoters, RpoHII produced detectable transcripts from only four promoters (cycA P1, groESL 1, hslO, and ecfE). These results, in combination with previous work demonstrating that an RpoHI mutant mounts a typical heat shock response, suggest that while RpoHI and RpoHII have redundant roles in response to heat, they may also have roles in response to other environmental stresses.

scholarly journals Inhibition of Transcription in Staphylococcus aureus by a Primary Sigma Factor-Binding Polypeptide from Phage G1

2009 ◽  
Vol 191 (12) ◽  
pp. 3763-3771 ◽  
Author(s):  
Mohammed Dehbi ◽  
Gregory Moeck ◽  
Francis F. Arhin ◽  
Pascale Bauda ◽  
Dominique Bergeron ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Rna Polymerase ◽  
Sigma Factor ◽  
Exponential Growth Phase ◽  
E Coli ◽  
Growth Inhibitory ◽  
Σ Factor ◽  
Transcription In Vitro

ABSTRACT The primary sigma factor of Staphylococcus aureus, σSA, regulates the transcription of many genes, including several essential genes, in this bacterium via specific recognition of exponential growth phase promoters. In this study, we report the existence of a novel staphylococcal phage G1-derived growth inhibitory polypeptide, referred to as G1ORF67, that interacts with σSA both in vivo and in vitro and regulates its activity. Delineation of the minimal domain of σSA that is required for its interaction with G1ORF67 as amino acids 294 to 360 near the carboxy terminus suggests that the G1 phage-encoded anti-σ factor may occlude the −35 element recognition domain of σSA. As would be predicted by this hypothesis, the G1ORF67 polypeptide abolished both RNA polymerase core-dependent binding of σSA to DNA and σSA-dependent transcription in vitro. While G1ORF67 profoundly inhibits transcription when expressed in S. aureus cells in mode of action studies, our finding that G1ORF67 was unable to inhibit transcription when expressed in Escherichia coli concurs with its inability to inhibit transcription by the E. coli holoenzyme in vitro. These features demonstrate the selectivity of G1ORF67 for S. aureus RNA polymerase. We predict that G1ORF67 is one of the central polypeptides in the phage G1 strategy to appropriate host RNA polymerase and redirect it to phage reproduction.

scholarly journals Recognition of Streptococcal Promoters by the Pneumococcal SigA Protein

2021 ◽  
Vol 8 ◽  
Author(s):  
Virtu Solano-Collado ◽  
Sofía Ruiz-Cruz ◽  
Fabián Lorenzo-Díaz ◽  
Radoslaw Pluta ◽  
Manuel Espinosa ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Sigma Factor ◽  
Regulation Of Gene Expression ◽  
E Coli ◽  
Core Enzyme ◽  
Protein Architecture ◽  
Bacterial Rna ◽  
Promoter Recognition ◽  
Rna Polymerase Holoenzyme

Promoter recognition by RNA polymerase is a key step in the regulation of gene expression. The bacterial RNA polymerase core enzyme is a complex of five subunits that interacts transitory with one of a set of sigma factors forming the RNA polymerase holoenzyme. The sigma factor confers promoter specificity to the RNA polymerase. In the Gram-positive pathogenic bacterium Streptococcus pneumoniae, most promoters are likely recognized by SigA, a poorly studied housekeeping sigma factor. Here we present a sequence conservation analysis and show that SigA has similar protein architecture to Escherichia coli and Bacillus subtilis homologs, namely the poorly conserved N-terminal 100 residues and well-conserved rest of the protein (domains 2, 3, and 4). Further, we have purified the native (untagged) SigA protein encoded by the pneumococcal R6 strain and reconstituted an RNA polymerase holoenzyme composed of the E. coli core enzyme and the sigma factor SigA (RNAP-SigA). By in vitro transcription, we have found that RNAP-SigA was able to recognize particular promoters, not only from the pneumococcal chromosome but also from the S. agalactiae promiscuous antibiotic-resistance plasmid pMV158. Specifically, SigA was able to direct the RNA polymerase to transcribe genes involved in replication and conjugative mobilization of plasmid pMV158. Our results point to the versatility of SigA in promoter recognition and its contribution to the promiscuity of plasmid pMV158.

scholarly journals GreA and GreB enhanceEscherichia coliRNA polymerase transcription rate in a reconstituted transcription-translation system

2015 ◽  
Author(s):  
Lea L. De Maddalena ◽  
Henrike Niederholtmeyer ◽  
Matti Turtola ◽  
Zoe Swank ◽  
Georgiy A. Belogurov ◽  
...  
Keyword(s):  
Synthetic Biology ◽  
Rna Polymerase ◽  
Sigma Factor ◽  
Expression System ◽  
Genetic Networks ◽  
Translation System ◽  
Transcription Rate ◽  
Pure System ◽  
E Coli

Cell-free environments are becoming viable alternatives for implementing biological networks in synthetic biology. The reconstituted cell-free expression system (PURE) allows characterization of genetic networks under defined conditions but its applicability to native bacterial promoters and endogenous genetic networks is limited due to the poor transcription rate ofEscherichia coliRNA polymerase in this minimal system. We found that addition of transcription elongation factors GreA and GreB to the PURE system increased transcription rates ofE. coliRNA polymerase from sigma factor 70 promoters up to 6-fold and enhanced the performance of a genetic network. Furthermore, we reconstituted activation of naturalE. colipromoters controlling flagella biosynthesis by the transcriptional activator FlhDC and sigma factor 28. Addition of GreA/GreB to the PURE system allows efficient expression from natural and syntheticE. colipromoters and characterization of their regulation in minimal and defined reaction conditions making the PURE system more broadly applicable to study genetic networks and bottom-up synthetic biology.

scholarly journals A mutant RNA polymerase activates the general stress response, enabling E. coli adaptation to late prolonged stationary phase

2020 ◽  
Author(s):  
Pabitra Nandy ◽  
Savita Chib ◽  
Aswin Seshasayee
Keyword(s):  
Stress Response ◽  
Rna Polymerase ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Slow Growth ◽  
General Mechanism ◽  
General Stress Response ◽  
E Coli ◽  
General Stress ◽  
Small Colony

AbstractEscherichia coli populations undergo repeated replacement of parental genotypes with fitter variants deep in stationary phase. We isolated one such variant, which emerged after three weeks o of maintaining an E. coli K12 population in stationary phase. This variant displayed a small colony phenotype, slow growth and was able to outcompete its ancestor over a narrow time window in stationary phase. The variant also shows tolerance to beta-lactam antibiotics, though not previously exposed to the antibiotic. We show that an RpoC (A494V) mutation confers the slow growth and small colony phenotype to this variant. The ability of this mutation to confer a growth advantage in stationary phase depends on the availability of the stationary phase sigma factor σS. The RpoC (A494V) mutation up-regulates the σS regulon. As shown over 20 years ago, early in prolonged stationary phase, σS attenuation, but not complete loss of activity, confers a fitness advantage. Our study shows that later mutations enhance σS activity, either by mutating the gene for σS directly, or via mutations such as RpoC (A494V). The balance between the activities of the housekeeping major sigma factor and σS sets up a trade-off between growth and stress tolerance, which is tuned repeatedly during prolonged stationary phase.ImportanceAn important general mechanism of bacterial adaptation to its environment involves adjusting the balance between growing fast, and tolerating stresses. One paradigm where this plays out is in prolonged stationary phase: early studies showed that attenuation, but not complete elimination, of the general stress response enables early adaptation of the bacterium E. coli to the conditions established about 10 days into stationary phase. We show here that this balance is not static and that it is tilted back in favour of the general stress response about two weeks later. This can be established by direct mutations in the master regulator of the general stress response, or by mutations in the core RNA polymerase enzyme itself. These conditions can support the development of antibiotic tolerance though the bacterium is not exposed to the antibiotic. Further exploration of the growth-stress balance over the course of stationary phase will necessarily require a deeper understanding of the events in the extracellular milieu.

RNA polymerase: Preparation and structural analysis of helical polymers

1984 ◽  
Vol 42 ◽  
pp. 152-153
Author(s):  
E. Loren Buhle ◽  
Pamela Rew ◽  
Ueli Aebi
Keyword(s):  
Structural Analysis ◽  
Rna Polymerase ◽  
Molecular Level ◽  
X Ray Diffraction ◽  
Helical Polymers ◽  
X Ray ◽  
E Coli ◽  
The Past ◽  
Ordered Arrays ◽  
Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

Sign in / Sign up

Export Citation Format

Share Document