scholarly journals Construction of Genetic Logic Gates Based on the T7 RNA Polymerase Expression System in Rhodococcus opacus PD630

2019 ◽  
Vol 8 (8) ◽  
pp. 1921-1930 ◽  
Author(s):  
Drew M. DeLorenzo ◽  
Tae Seok Moon
Keyword(s):  
Rna Polymerase ◽  
Expression System ◽  
Logic Gates ◽  
T7 Rna Polymerase ◽  
Rhodococcus Opacus ◽  
Rhodococcus Opacus Pd630

High-level transcription of large gene regions: a novel T7 RNA-polymerase-based system for expression of functional hydrogenases in the phototrophic bacterium Rhodobacter capsulatus

2005 ◽  
Vol 33 (1) ◽  
pp. 56-58 ◽  
Author(s):  
T. Drepper ◽  
S. Arvani ◽  
F. Rosenau ◽  
S. Wilhelm ◽  
K.-E. Jaeger
Keyword(s):  
Rna Polymerase ◽  
Rhodobacter Capsulatus ◽  
Expression System ◽  
Active Form ◽  
T7 Rna Polymerase ◽  
High Level Synthesis ◽  
Phototrophic Bacterium ◽  
Large Gene ◽  
High Level ◽  
Complex Enzymes

High-level synthesis of complex enzymes like bacterial [NiFe] hydrogenases, in general, requires an expression system that allows concerted expression of a large number of genes. So far, it has not been possible to overproduce a hydrogenase in a stable and active form by using a customary expression system. Therefore we started to establish a new, T7-based expression system in the phototrophic bacterium Rhodobacter capsulatus. The beneficial properties of this bacterial host in combination with the unique capacity of T7 RNA polymerase to synthesize long transcripts will allow the high-level synthesis and assembly of active hydrogenase as well as other complex enzymes in the near future.

scholarly journals Engineering efficient termination of bacteriophage T7 RNA polymerase transcription

2021 ◽  
Author(s):  
Diana Gabriela Calvopina Chavez ◽  
Mikaela Anne Gardner ◽  
Joel S Griffitts
Keyword(s):  
Rna Polymerase ◽  
Molecular Level ◽  
Expression System ◽  
T7 Rna Polymerase ◽  
Bacteriophage T7 ◽  
Lower Efficiency ◽  
Transcriptional Termination ◽  
T7 Polymerase

The bacteriophage T7 expression system is one of the most prominent transcription systems used in biotechnology and molecular-level research. However, T7 RNA polymerase is prone to read-through transcription due to its high processivity. As a consequence, enforcing efficient transcriptional termination is difficult. The termination hairpin found natively in the T7 genome is adapted to be inefficient, exhibiting 62% termination efficiency in vivo and even lower efficiency in vitro. In this study, we engineered a series of sequences that outperform the efficiency of the native terminator hairpin. By embedding a previously discovered 8-nucleotide T7 polymerase pause sequence within a synthetic hairpin sequence, we observed in vivo termination efficiency of 91%; by joining two short sequences into a tandem 2-hairpin structure, termination efficiency was increased to 98% in vivo and 91% in vitro. This study also tests the ability of these engineered sequences to terminate transcription of the Escherichia coli RNA polymerase. Two out of three of the most successful T7 polymerase terminators also facilitated termination of the bacterial polymerase with around 99% efficiency.

scholarly journals Synthetic logic circuits using RNA aptamer against T7 RNA polymerase

2014 ◽  
Author(s):  
Jongmin Kim ◽  
Juan F Quijano ◽  
Enoch Yeung ◽  
Richard M Murray
Keyword(s):  
Rna Polymerase ◽  
Expression System ◽  
Building Blocks ◽  
Logic Circuits ◽  
T7 Rna Polymerase ◽  
Free Expression ◽  
Rna Aptamer ◽  
Cell Free Expression System

Recent advances in nucleic acids engineering introduced several RNA-based regulatory components for synthetic gene circuits, expanding the toolsets to engineer organisms. In this work, we designed genetic circuits implementing an RNA aptamer previously described to have the capability of binding to the T7 RNA polymerase and inhibiting its activity in vitro. Using in vitro transcription assays, we first demonstrated the utility of the RNA aptamer in combination with programmable synthetic transcription networks. As a step to quickly assess the feasibility of aptamer functions in vivo, a cell-free expression system was used as a breadboard to emulate the in vivo conditions of E. coli. We tested the aptamer and its three sequence variants in the cell-free expression system, verifying the aptamer functionality in the cell-free testbed. In vivo expression of aptamer and its variants demonstrated control over GFP expression driven by T7 RNA polymerase with different response curves, indicating its ability to serve as building blocks for both logic circuits and transcriptional cascades. This work elucidates the potential of RNA-based regulators for cell programming with improved controllability leveraging the fast production and degradation time scales of RNA molecules.

scholarly journals Regulating the T7 RNA polymerase expression in E. coli BL21 (DE3) to provide more host options for recombinant protein production

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Fei Du ◽  
Yun-Qi Liu ◽  
Ying-Shuang Xu ◽  
Zi-Jia Li ◽  
Yu-Zhou Wang ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Rna Polymerase ◽  
Recombinant Proteins ◽  
Expression System ◽  
T7 Rna Polymerase ◽  
Expression Level ◽  
Foreign Protein ◽  
Atpase Subunit ◽  
E Coli ◽  
Prokaryotic Expression System

AbstractEscherichia coli is the most widely used bacterium in prokaryotic expression system for the production of recombinant proteins. In BL21 (DE3), the gene encoding the T7 RNA polymerase (T7 RNAP) is under control of the strong lacUV5 promoter (PlacUV5), which is leakier and more active than wild-type lac promoter (PlacWT) under certain growth conditions. These characteristics are not advantageous for the production of those recombinant proteins with toxic or growth-burdened. On the one hand, leakage expression of T7 RNAP leads to rapid production of target proteins under non-inducing period, which sucks resources away from cellular growth. Moreover, in non-inducing or inducing period, high expression of T7 RNAP production leads to the high-production of hard-to-express proteins, which may all lead to loss of the expression plasmid or the occurrence of mutations in the expressed gene. Therefore, more BL21 (DE3)-derived variant strains with rigorous expression and different expression level of T7 RNAP should be developed. Hence, we replaced PlacUV5 with other inducible promoters respectively, including arabinose promoter (ParaBAD), rhamnose promoter (PrhaBAD), tetracycline promoter (Ptet), in order to optimize the production of recombinant protein by regulating the transcription level and the leakage level of T7 RNAP. Compared with BL21 (DE3), the constructed engineered strains had higher sensitivity to inducers, among which rhamnose and tetracycline promoters had the lowest leakage ability. In the production of glucose dehydrogenase (GDH), a protein that causes host autolysis, the engineered strain BL21 (DE3::ara) exhibited higher biomass, cell survival rate and foreign protein expression level than that of BL21 (DE3). In addition, these engineered strains had been successfully applied to improve the production of membrane proteins, including E. coli cytosine transporter protein (CodB), the E. coli membrane protein insertase/foldase (YidC), and the E. coli F-ATPase subunit b (Ecb). The engineered strains constructed in this paper provided more host choices for the production of recombinant proteins.

scholarly journals The optimization of cytoplasmic gene expression system with T7 RNA polymerase.

1998 ◽  
Vol 13 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Ryo Suzuki ◽  
Tetsuhiko Nakagawa ◽  
Hiroyuki Mizuguchi ◽  
Susumu Imazu ◽  
Tsuyoshi Nakanishi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Expression System ◽  
T7 Rna Polymerase ◽  
Gene Expression System

CRISPR/Cas9 mediated T7 RNA polymerase gene knock-in in E. coli BW25113 makes T7 expression system work efficiently

2021 ◽  
Author(s):  
Changchuan Ye ◽  
Xi Chen ◽  
Mengjie Yang ◽  
Xiangfang Zeng ◽  
Shiyan Qiao
Keyword(s):  
Rna Polymerase ◽  
Mutant Strain ◽  
Aminolevulinic Acid ◽  
Expression System ◽  
T7 Rna Polymerase ◽  
Bacterial Strains ◽  
T7 Promoter ◽  
E Coli ◽  
T7 Expression System ◽  
High Level

Abstract T7 Expression System is a common method of ensuring tight control and high-level induced expression. However, this system can only work in some bacterial strains in which the T7 RNA Polymerase gene resides in the chromosome. In this study, we successfully introduced a chromosomal copy of the T7 RNA Polymerase gene under control of the lacUV5 promoter into Escherichia coli BW25113. The T7 Expression System worked efficiently in this mutant strain named BW25113-T7. We demonstrated that this mutant strain could satisfactorily produce 5-Aminolevulinic Acid via C5 pathway. A final study was designed to enhance the controllability of T7 Expression System in this mutant strain by constructing a T7 Promoter Variants Library. These efforts advanced E. coli BW25113-T7 to be a practical host for future metabolic engineering efforts.

T7 RNA polymerase-dependent expression of COXII in yeast mitochondria

1994 ◽  
Vol 14 (7) ◽  
pp. 4643-4652
Author(s):  
J L Pinkham ◽  
A M Dudley ◽  
T L Mason
Keyword(s):  
Mitochondrial Genome ◽  
Rna Polymerase ◽  
Target Gene ◽  
Expression System ◽  
T7 Rna Polymerase ◽  
Cellular Respiration ◽  
Detectable Effect ◽  
Wild Type ◽  
Cox2 Expression ◽  
Adh1 Promoter

An in vivo expression system has been developed for controlling the transcription of individual genes in the mitochondrial genome of Saccharomyces cerevisiae. The bacteriophage T7 RNA polymerase (T7Pol), fused to the COXIV mitchondrial import peptide and expressed under the control of either the GAL1 or the ADH1 promoter, efficiently transcribes a target gene, T7-COX2, in the mitochondrial genome. Cells bearing the T7-COX2 gene, but lacking wild-type COX2, require T7Pol for respiration. Functional expression of T7-COX2 is completely dependent on the COX2-specific translational activator Pet111p, despite additional nucleotides at the 5' end of the T7-COX2 transcript. Expression of mitochondrion-targeted T7Pol at high levels from the GAL1 promoter has no detectable effect on mitochondrial function in rho+ cells lacking the T7-COX2 target gene, but in cells with T7-COX2 integrated into the mitochondrial genome, an equivalent level of T7Pol expression causes severe respiratory deficiency. In comparison with wild-type COX2 expression, steady-state levels of T7-COX2 mRNA increase fivefold when transcription is driven by T7Pol expressed from the ADH1 promoter, yet COXII protein levels and cellular respiration rates decrease by about 50%. This discoordinate expression of mRNA and protein provides additional evidence for posttranscriptional control of COX2 expression.

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