scholarly journals An Estradiol-Inducible Promoter Enables Fast, Graduated Control of Gene Expression in Fission Yeast

2016 ◽  
Author(s):  
Makoto J. Ohira ◽  
David G. Hendrickson ◽  
R. Scott McIsaac ◽  
Nicholas Rhind

ABSTRACTThe fission yeast Schizosaccharomyces pombe lacks a diverse toolkit of inducible promoters for experimental manipulation. Available inducible promoters suffer from slow induction kinetics, limited control of expression levels and/or a requirement for defined growth medium. In particular, no S. pombe inducible promoter systems exhibit a linear dose response, which would allow expression to be tuned to specific levels. We have adapted a fast, orthogonal promoter system with a large dynamic range and a linear dose response, based on β-estradiol-regulated function of the human estrogen receptor, for use in S. pombe. We show that this promoter system, termed Z3EV, turns on quickly, can reach a maximal induction of 20 fold, and exhibits a linear dose response over its entire induction range, with few off target effects. We demonstrate the utility of this system by regulating the mitotic inhibitor Wee1 to create a strain in which cell size is regulated by β-estradiol concentration. This promoter system will be of great utility for experimentally regulating gene expression in fission yeast.

Biology Open ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. bio055343 ◽  
Author(s):  
Daniel Chu ◽  
An Nguyen ◽  
Spenser S. Smith ◽  
Zuzana Vavrušová ◽  
Richard A. Schneider

ABSTRACTPrecisely altering gene expression is critical for understanding molecular processes of embryogenesis. Although some tools exist for transgene misexpression in developing chick embryos, we have refined and advanced them by simplifying and optimizing constructs for spatiotemporal control. To maintain expression over the entire course of embryonic development we use an enhanced piggyBac transposon system that efficiently integrates sequences into the host genome. We also incorporate a DNA targeting sequence to direct plasmid translocation into the nucleus and a D4Z4 insulator sequence to prevent epigenetic silencing. We designed these constructs to minimize their size and maximize cellular uptake, and to simplify usage by placing all of the integrating sequences on a single plasmid. Following electroporation of stage HH8.5 embryos, our tetracycline-inducible promoter construct produces robust transgene expression in the presence of doxycycline at any point during embryonic development in ovo or in culture. Moreover, expression levels can be modulated by titrating doxycycline concentrations and spatial control can be achieved using beads or gels. Thus, we have generated a novel, sensitive, tunable, and stable inducible-promoter system for high-resolution gene manipulation in vivo.


Yeast ◽  
2017 ◽  
Vol 34 (8) ◽  
pp. 323-334 ◽  
Author(s):  
Makoto J. Ohira ◽  
David G. Hendrickson ◽  
R. Scott McIsaac ◽  
Nicholas Rhind

2017 ◽  
Author(s):  
Ciarán L. Kelly ◽  
Andrew Hitchcock ◽  
Antonio Torres-Méndez ◽  
John T. Heap

ABSTRACTCyanobacteria are important for fundamental studies of photosynthesis and have great biotechnological potential. In order to better study and fully exploit these organisms, the limited repertoire of genetic tools and parts must be expanded. A small number of inducible promoters have been used in cyanobacteria, allowing dynamic external control of gene expression through the addition of specific inducer molecules. However, the inducible promoters used to date suffer from various drawbacks including toxicity of inducers, leaky expression in the absence of inducer and inducer photolability, the latter being particularly relevant to cyanobacteria which, as photoautotrophs, are grown under light. Here we introduce the rhamnose-induciblerhaBADpromoter ofEscherichia coliinto the model freshwater cyanobacteriumSynechocystissp. PCC 6803 and demonstrate it has superior properties to previously reported cyanobacterial inducible promoter systems, such as a non-toxic, photostable, non-metabolizable inducer, a linear response to inducer concentration and crucially no basal transcription in the absence of inducer.


Author(s):  
Andrew M Hogan ◽  
Kevin R Jeffers ◽  
Armando Palacios ◽  
Silvia T Cardona

A diverse genetic toolkit is critical for understanding bacterial physiology and genotype-phenotype relationships. Inducible promoter systems are an integral part of this toolkit. In Burkholderia and related species, the L-rhamnose-inducible promoter is among the first choices due to its tight control and the lack of viable alternatives. To improve upon its maximum activity and dynamic range, we explored the effect of promoter system modifications in B. cenocepacia with a LacZ-based reporter. By combining the bacteriophage T7 gene 10 stem loop and engineered rhaI transcription factor-binding sites, we obtained a rhamnose-inducible system with a 6.5-fold and 3.0-fold increase in maximum activity and dynamic range, respectively, compared to the native promoter. We then added the modified promoter system to pSCrhaB2 and pSC201, common genetic tools used for plasmid-based and chromosome-based gene expression, respectively, in Burkholderia, creating pSCrhaB2plus and pSC201plus. We demonstrated the utility of pSCrhaB2plus for gene expression in B. thailandensis , B. multivorans and B. vietnamiensis and used pSC201plus to control highly expressed essential genes from the chromosome of B. cenocepacia . The utility of the modified system was demonstrated as we recovered viable mutants to control ftsZ , rpoBC , and rpsF , whereas the unmodified promoter was unable to control rpsF . The modified expression system allowed control of an essential gene depletion phenotype at lower levels of L-rhamnose, the inducer. pSCRhaB2plus and pSC201plus are expected to be valuable additions to the genetic toolkit for Burkholderia and related species. Importance Species of Burkholderia are dually recognized as being of attractive biotechnological potential but also opportunistic pathogens for immunocompromised individuals. Understanding the genotype-phenotype relationship is critical for synthetic biology approaches in Burkholderia to disentangle pathogenic from beneficial traits. A diverse genetic toolkit, including inducible promoters, is the foundation for these investigations. We thus sought to improve on the commonly used rhamnose-inducible promoter system. Our modifications resulted in both higher levels of heterologous protein expression and broader control over highly-expressed essential genes in B. cenocepacia . The significance of our work is in expanding the genetic toolkit to enable more comprehensive studies into Burkholderia and related bacteria.


2020 ◽  
Author(s):  
Daniel Chu ◽  
An Nguyen ◽  
Spenser S. Smith ◽  
Zuzana Vavrušová ◽  
Richard A. Schneider

AbstractPrecisely altering gene expression is critical for understanding molecular processes of embryogenesis. Although some tools exist for transgene misexpression in developing chick embryos, we have refined and advanced them by simplifying and optimizing constructs for spatiotemporal control. To maintain expression over the entire course of embryonic development we use an enhanced piggyBac transposon system that efficiently integrates sequences into the host genome. We also incorporate a DNA targeting sequence to direct plasmid translocation into the nucleus and a D4Z4 insulator sequence to prevent epigenetic silencing. We designed these constructs to minimize their size and maximize cellular uptake, and to simplify usage by placing all of the integrating sequences on a single plasmid. Following electroporation of stage HH8.5 embryos, our tetracycline-inducible promoter construct produces robust transgene expression in the presence of doxycycline at any point during embryonic development in ovo or in culture. Moreover, expression levels can be modulated by titrating doxycycline concentrations and spatial control can be achieved using beads or gels. Thus, we have generated a novel, sensitive, tunable, and stable inducible-promoter system for high-resolution gene manipulation in vivo.


2020 ◽  
Author(s):  
Jake D. Callaghan ◽  
Nicholas A. Stella ◽  
Kara M. Lehner ◽  
Benjamin R. Treat ◽  
Kimberly M. Brothers ◽  
...  

ABSTRACTTunable control of gene expression is an invaluable tool for biological experiments. In this study, we describe a new xylose-inducible promoter system and evaluate it in both Pseudomonas aeruginosa and P. fluorescens. The Pxut promoter derived from the P. flurorescens xut operon was incorporated into a broad host-range pBBR1-based plasmid and compared to the Escherichia coli-derived PBAD promoter using gfp as a reporter. GFP-fluorescence from the Pxut promoter was inducible in both Pseudomonas species, but not in E. coli, which may facilitate cloning of toxic genes using E. coli to generate plasmids. The Pxut promoter was expressed at a lower inducer concentration than PBAD in P. fluorescens and higher gfp levels were achieved using Pxut. Flow cytometry analysis indicated that Pxut was more leaky than PBAD in the tested Pseudomonas species, but was expressed in a higher proportion of cells when induced. D-xylose did not support growth of P. aeruginosa or P. fluorescens as a sole carbon source and is less expensive than many other commonly used inducers which could facilitate large scale applications. The efficacy of this system aided in demonstrating a role for the P. aeruginosa type II secretion system gene from xcpQ in bacterial inhibition of corneal epithelial cell wound closure. This study introduces a new inducible promoter system for gene expression for use in Pseudomonas species.ImportancePseudomonas species are enormously important in human infections, biotechnology, and as a model system for interrogating basic science questions. In this study we have developed a xylose-inducible promoter system and evaluated it in P. aeruginosa and P. fluorescens and found it to be suitable for the strong induction of gene expression. Furthermore, we have demonstrated its efficacy in controlled gene expression to show that a type 2 secretion system protein from P. aeruginosa, XcpQ, is important for host-pathogen interactions in a corneal wound closure model.


2010 ◽  
Vol 77 (2) ◽  
pp. 471-478 ◽  
Author(s):  
Andrea H. Hartman ◽  
Hualan Liu ◽  
Stephen B. Melville

ABSTRACTClostridium perfringensis a Gram-positive anaerobic pathogen which causes many diseases in humans and animals. While some genetic tools exist for working withC. perfringens, a tightly regulated, inducible promoter system is currently lacking. Therefore, we constructed a plasmid-based promoter system that provided regulated expression when lactose was added. This plasmid (pKRAH1) is anEscherichia coli-C. perfringensshuttle vector containing the gene encoding a transcriptional regulator, BgaR, and a divergent promoter upstream of genebgaL(bgaR-PbgaL). To measure transcription at thebgaLpromoter in pKRAH1, theE. colireporter genegusA, encoding β-glucuronidase, was placed downstream of the PbgaLpromoter to make plasmid pAH2. When transformed into three strains ofC. perfringens, pAH2 exhibited lactose-inducible expression.C. perfringensstrain 13, a commonly studied strain, has endogenous β-glucuronidase activity. We mutated genebglR, encoding a putative β-glucuronidase, and observed an 89% decrease in endogenous activity with no lactose. This combination of a system for regulated gene expression and a mutant of strain 13 with low β-glucuronidase activity are useful tools for studying gene regulation and protein expression in an important pathogenic bacterium. We used this system to express theyfp-pilBgene, comprised of a yellow fluorescent protein (YFP)-encoding gene fused to an assembly ATPase gene involved in type IV pilus-dependent gliding motility inC. perfringens. Expression in the wild-type strain showed that YFP-PilB localized mostly to the poles of cells, but in apilCmutant it localized throughout the cell, demonstrating that the membrane protein PilC is required for polar localization of PilB.


eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Sachin Sethi ◽  
Jing W Wang

Several techniques have been developed to manipulate gene expression temporally in intact neural circuits. However, the applicability of current tools developed for in vivo studies in Drosophila is limited by their incompatibility with existing GAL4 lines and side effects on physiology and behavior. To circumvent these limitations, we adopted a strategy to reversibly regulate protein degradation with a small molecule by using a destabilizing domain (DD). We show that this system is effective across different tissues and developmental stages. We further show that this system can be used to control in vivo gene expression levels with low background, large dynamic range, and in a reversible manner without detectable side effects on the lifespan or behavior of the animal. Additionally, we engineered tools for chemically controlling gene expression (GAL80-DD) and recombination (FLP-DD). We demonstrate the applicability of this technology in manipulating neuronal activity and for high-efficiency sparse labeling of neuronal populations.


2017 ◽  
Author(s):  
Sachin Sethi ◽  
Jing W. Wang

AbstractSeveral techniques have been developed to manipulate gene expression temporally in intact neural circuits. However, the applicability of current tools developed for in vivo studies in Drosophila is limited by their incompatibility with existing GAL4 lines and side effects on physiology and behavior. To circumvent these limitations, we adopted a strategy to reversibly regulate protein degradation with a small molecule by using a destabilizing domain (DD). We show that this system is effective across different tissues and developmental stages. We further show that this system can be used to control in vivo gene expression levels with low background, large dynamic range, and in a reversible manner without detectable side effects on the lifespan or behavior of the animal. Additionally, we engineered tools for chemically controlling gene expression (GAL80-DD) and recombination (FLP-DD). We demonstrate the applicability of this technology in manipulating neuronal activity and for high-efficiency sparse labeling of neuronal populations.


2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Jake D. Callaghan ◽  
Nicholas A. Stella ◽  
Kara M. Lehner ◽  
Benjamin R. Treat ◽  
Kimberly M. Brothers ◽  
...  

ABSTRACT Tunable control of gene expression is an invaluable tool for biological experiments. In this study, we describe a new xylose-inducible promoter system and evaluate it in both Pseudomonas aeruginosa and Pseudomonas fluorescens. The Pxut promoter, derived from the P. fluorescens xut operon, was incorporated into a broad-host-range pBBR1-based plasmid and was compared to the Escherichia coli-derived PBAD promoter using gfp as a reporter. Green fluorescent protein (GFP) fluorescence from the Pxut promoter was inducible in both Pseudomonas species, but not in E. coli, which may facilitate the cloning of genes toxic to E. coli to generate plasmids. The Pxut promoter was activated at a lower inducer concentration than PBAD in P. fluorescens, and higher gfp levels were achieved using Pxut. Flow cytometry analysis indicated that Pxut was leakier than PBAD in the Pseudomonas species tested but was expressed in a higher proportion of cells when induced. d-Xylose as a sole carbon source did not support the growth of P. aeruginosa or P. fluorescens and is less expensive than many other commonly used inducers, which could facilitate large-scale applications. The efficacy of this system was demonstrated by its use to reveal a role for the P. aeruginosa type II secretion system gene xcpQ in bacterial inhibition of corneal epithelial cell wound closure. This study introduces a new inducible promoter system for gene expression for use in Pseudomonas species. IMPORTANCE Pseudomonas species are enormously important in human infections, in biotechnology, and as model systems for investigating basic science questions. In this study, we have developed a xylose-inducible promoter system, evaluated it in P. aeruginosa and P. fluorescens, and found it to be suitable for the strong induction of gene expression. Furthermore, we have demonstrated its efficacy in controlled gene expression to show that a type II secretion system protein from P. aeruginosa, XcpQ, is important for host-pathogen interactions in a corneal wound closure model.


Sign in / Sign up

Export Citation Format

Share Document