Gene/Protein Disease Symptom Drug Enzyme Compound
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 78,556 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression from the Escherichia coli nrfA promoter (pnrfA) is activated by both the FNR protein (an anaerobically triggered transcription activator) and the NarL or NarP proteins (transcription activators triggered by nitrite and nitrate). Under anaerobic conditions, FNR binds to a site centred at position -41.5 at pnrfA and activates transcription. Further activation, induced by the presence of nitrite, results from the binding of NarL and NarP to a site centred at position -74.5. A second promoter (pacsP1), which directs transcription into the adjacent gene encoding acetyl coenzyme A synthetase (acs), is overlapping and divergent to pnrfA. Despite extensive overlap of regulatory elements, pnrfA and pacsP1 are regulated independently. We demonstrate that at least two nucleoid-associated factors bind to the nrfA-acs intergenic region. The Fis protein binds to a site centred at position -15 (in relation to pnrfA transcription), whereas the IHF protein binds to a site centred at position -54. Both Fis and IHF repress in vivo expression from pacsP1, but have smaller repressive effects on expression from pnrfA. Gel retardation assays were used to investigate the pairwise binding of FNR, NarL, Fis and IHF proteins to the nrfA-acs intergenic region. The binding of NarL and IHF is mutually exclusive, whereas all other combinations can bind simultaneously. Experiments in which deletions and point mutations were introduced into the upstream region of pnrfA demonstrated that an additional factor must bind upstream to inhibit FNR-dependent transcription. We conclude that the nrfA-acs intergenic region is folded into an ordered nucleoprotein structure that permits the two divergent promoters to be regulated independently in response to different physiological signals.
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PMID:Independent regulation of the divergent Escherichia coli nrfA and acsP1 promoters by a nucleoprotein assembly at a shared regulatory region. 1192 25

Thinopyrum intermedium is resistant to many different pathogens. To understand the roles of ethylene response factors (ERFs) in defence responses, the first member of the ERF family in T. intermedium, TiERF1, was characterized and functionally analysed in this study. The TiERF1 gene encodes a putative protein of 292 amino acids, belonging to the B3 subgroup of the ERF transcription factor family. Biochemical assays demonstrated that the TiERF1 protein is capable of binding to the GCC box, a cis-element present in the promoters of pathogenesis-related (PR) genes, and possessing transactivation activity, as well as localizing to the nucleus. The transcript of TiERF1 in T. intermedium is rapidly induced by infection with Rhizoctonia cerealis, Fusarium graminearum, or Blumeria graminis, and ethylene, jasmonic acid, and salicylic acid treatments. More importantly, the ectopic expression of TiERF1 in tobacco activated the transcript of the PR genes of tobacco with a GCC box cis-element, and ACO and ACS genes key to ethylene synthesis, and in turn improved the resistance level to Alternaria alternata and tobacco mosaic virus, as well as causing some phenotypic changes associated with ethylene response in the transgenic tobacco plants. Taken together, TiERF1 protein as an ERF transcription activator positively regulates defence responses via the activation of some defence-related genes.
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PMID:A novel activator-type ERF of Thinopyrum intermedium, TiERF1, positively regulates defence responses. 1861 11

Recombinant transcription activator-like effectors (TALEs) have been effectively used for genome editing and gene regulation applications. Due to their remarkable modularity, TALEs can be tailored to specifically target almost any user-defined DNA sequences. Here, we introduce fairyTALE, a liquid phase high-throughput TALE synthesis platform capable of producing TALE-nucleases, activators, and repressors that recognize DNA sequences between 14 and 31 bp. It features a highly efficient reaction scheme, a flexible functionalization platform, and fully automated robotic liquid handling that enable the production of hundreds of expression-ready TALEs within a single day with over 98% assembly efficiency at a material cost of just $5 per TALE. As proof of concept, we synthesized and tested 90 TALEs, each recognizing 27 bp, without restrictions on their sequence composition. 96% of these TALEs were found to be functional, while sequencing confirmation revealed that the nonfunctional constructs were all correctly assembled.
ACS Synth Biol 2014 Feb 21
PMID:FairyTALE: a high-throughput TAL effector synthesis platform. 2423 14

The construction of increasingly sophisticated synthetic biological circuits is dependent on the development of extensible tools capable of providing specific control of gene expression in eukaryotic cells. Here, we describe a new class of synthetic transcription factors that activate gene expression in response to extracellular chemical stimuli. These inducible activators consist of customizable transcription activator-like effector (TALE) proteins combined with steroid hormone receptor ligand-binding domains. We demonstrate that these ligand-responsive TALE transcription factors allow for tunable and conditional control of gene activation and can be used to regulate the expression of endogenous genes in human cells. Since TALEs can be designed to recognize any contiguous DNA sequence, the conditional gene regulatory system described herein will enable the design of advanced synthetic gene networks.
ACS Synth Biol 2014 Oct 17
PMID:Regulation of endogenous human gene expression by ligand-inducible TALE transcription factors. 2425 25

Genome editing is an important tool for building novel genotypes with a desired phenotype. However, the fundamental challenge is to rapidly generate desired alterations on a genome-wide scale. Here, we report TALENs (transcription activator-like effector nucleases)-assisted multiplex editing (TAME), based on the interaction of designed TALENs with the DNA sequences between the critical TATA and GC boxes, for generating multiple targeted genomic modifications. Through iterative cycles of TAME to induce abundant semirational indels coupled with efficient screening using a reporter, the targeted fluorescent trait can be continuously and rapidly improved by accumulating multiplex beneficial genetic modifications in the evolving yeast genome. To further evaluate its efficiency, we also demonstrate the application of TAME for significantly improving ethanol tolerance of yeast in a short amount of time. Therefore, TAME is a broadly generalizable platform for accelerated genome evolution to rapidly improve yeast phenotypes.
ACS Synth Biol 2015 Oct 16
PMID:TALENs-Assisted Multiplex Editing for Accelerated Genome Evolution To Improve Yeast Phenotypes. 2601 Dec 97

Rats were the first mammalian species domesticated for scientific purposes, and they soon became the most widely used animal model in biomedical sciences, including cardiovascular research and behavioral neuroscience. Yet, after the development of technologies to manipulate genes, researchers largely shifted to the use of mice. However, as we lay out with examples from drug addiction, social behavior, and cardiovascular research, rats have experimental advantages over mice. With the introduction of zinc-finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN) methodologies, and, specifically, the clustered regularly interspaced short palindromic repeats (CRISPR) associated system, gene targeting is no longer limited to mice. Development of genetic technologies in rats allows researchers to take advantage of the unique opportunities offered by this species in biomedical research.
ACS Chem Neurosci 2017 05 17
PMID:Comeback of the Rat in Biomedical Research. 2818 97

Yarrowia lipolytica is a promising organism for the production of lipids of biotechnological interest and particularly for biofuel. In this study, we engineered the key enzyme involved in lipid biosynthesis, the giant multifunctional fatty acid synthase (FAS), to shorten chain length of the synthesized fatty acids. Taking as starting point that the ketoacyl synthase (KS) domain of Yarrowia lipolytica FAS is directly involved in chain length specificity, we used molecular modeling to investigate molecular recognition of palmitic acid (C16 fatty acid) by the KS. This enabled to point out the key role of an isoleucine residue, I1220, from the fatty acid binding site, which could be targeted by mutagenesis. To address this challenge, TALEN (transcription activator-like effector nucleases)-based genome editing technology was applied for the first time to Yarrowia lipolytica and proved to be very efficient for inducing targeted genome modifications. Among the generated FAS mutants, those having a bulky aromatic amino acid residue in place of the native isoleucine at position 1220 led to a significant increase of myristic acid (C14) production compared to parental wild-type KS. Particularly, the best performing mutant, I1220W, accumulates C14 at a level of 11.6% total fatty acids. Overall, this work illustrates how a combination of molecular modeling and genome-editing technology can offer novel opportunities to rationally engineer complex systems for synthetic biology.
ACS Synth Biol 2017 10 20
PMID:Production of Medium Chain Fatty Acids by Yarrowia lipolytica: Combining Molecular Design and TALEN to Engineer the Fatty Acid Synthase. 2858 17

Inducible modulation is often required for precise investigations and manipulations of dynamic biological processes. Transcription activator-like effectors (TALEs) provide a powerful tool for targeted gene editing and transcriptional programming. We designed a series of chemical inducible systems by coupling TALEs with a mutated human estrogen receptor (ERT2), which renders them 4-hydroxyl-tamoxifen (4-OHT) inducible for access of the genome. Chemical inducible genome editing was achieved via fusing two tandem ERT2 domains to customized transcription activator-like effector nuclease (TALEN), which we termed "Hybrid Inducible Technology" (HIT-TALEN). Those for transcription activation were vigorously optimized using multiple construct designs. Most efficient drug induction for endogenous gene activation was accomplished with minimal background activity using an optimized inducible TALE based SunTag system (HIT-TALE-SunTag). The HIT-SunTag system is rapid, tunable, selective to 4-OHT over an endogenous ligand, and reversible in drug induced transcriptional activation. Versatile systems developed in this study can be easily applied for editing and transcriptional programming of potentially any genomic loci in a tight and effective chemical inducible fashion.
ACS Chem Biol 2018 03 16
PMID:Multiple Chemical Inducible Tal Effectors for Genome Editing and Transcription Activation. 2930 80

The mitochondria DNA (mtDNA) editing tool, zinc finger nucleases (ZFNs), transcription activator-like effector nuclease (TALENs), and clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system, is a promising approach for the treatment of mtDNA diseases by eliminating mutant mitochondrial genomes. However, there have been no reports of repairing the mutant mtDNA with homologous recombination strategy to date. Here, we show a mito-CRISPR/Cas9 system that mito-Cas9 protein can specifically target mtDNA and reduce mtDNA copy number in both human cells and zebrafish. An exogenous single-stranded DNA with short homologous arm was knocked into the targeting loci accurately, and this mutagenesis could be steadily transmitted to F1 generation of zebrafish. Moreover, we found some major factors involved in nuclear DNA repair were upregulated significantly by the mito-CRISPR/Cas9 system. Taken together, our data suggested that the mito-CRISPR/Cas9 system could be a useful method to edit mtDNA by knock-in strategy, providing a potential therapy for the treatment of inherited mitochondrial diseases.
ACS Synth Biol 2019 04 19
PMID:Knock-In Strategy for Editing Human and Zebrafish Mitochondrial DNA Using Mito-CRISPR/Cas9 System. 3095 21

Stringency (low leak) is one of the most important specifications required for genetic circuits and induction systems, but it is challenging to evolve without sacrificing the maximum output level. This problem also comes from the absence of truly tunable negative selection methods. This paper reports that stringently switching variants can sometimes emerge with surprising frequency upon mutations. We randomly mutated the previously generated leaky variants of LuxR, the quorum-sensing transcription activator from Vibrio fischeri, to restore the stringency. We found as much as 10-20% of the entire population exhibited significantly improved signal-to-noise ratios compared with their parents. This indicated that these mutants arose by the loss of folding capability by accumulating destabilizing mutations, not by introducing rare adaptive mutations, thereby becoming AHL-dependent folders. Only four rounds of mutagenesis and ON-state selection resulted in the domination of the entire population by the improved variants with low leak, without direct selection pressure for stringency. With this surprising frequency, conversion into the "ligand-addicted folders" should be one of the prevailing modes of evolving stringency both in the laboratory and in nature, and the workflow described here provides a rapid and versatile method of improving the signal-to-noise ratio of various genetic switches.
ACS Synth Biol 2020 03 20
PMID:Directed Evolution of the Stringency of the LuxR Vibrio fischeri Quorum Sensor without OFF-State Selection. 3199 35


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