scholarly journals Model-driven promoter strength prediction based on a fine-tuned synthetic promoter library in Escherichia coli

2020 ◽  
Author(s):  
Mei Zhao ◽  
Shenghu Zhou ◽  
Longtao Wu ◽  
Yu Deng
Keyword(s):  
Metabolic Pathways ◽  
Regulatory Elements ◽  
Strength Prediction ◽  
Promoter Strength ◽  
Synthetic Promoter ◽  
Promoter Sequences ◽  
Model Driven ◽  
Promoter Library ◽  
Mutant Promoter ◽  
The Relationship

AbstractPromoters are one of the most critical regulatory elements controlling metabolic pathways. However, in recent years, researchers have simply perfected promoter strength, but ignored the relationship between the internal sequences and promoter strength. In this context, we constructed and characterized a mutant promoter library of Ptrc through dozens of mutation-construction-screening-characterization engineering cycles. After excluding invalid mutation sites, we established a synthetic promoter library, which consisted of 3665 different variants, displaying an intensity range of more than two orders of magnitude. The strongest variant was 1.52-fold stronger than a 1 mM isopropyl-β-D-thiogalactoside driven PT7 promoter. Our synthetic promoter library exhibited superior applicability when expressing different reporters, in both plasmids and the genome. Different machine learning models were built and optimized to explore relationships between the promoter sequences and transcriptional strength. Finally, our XgBoost model exhibited optimal performance, and we utilized this approach to precisely predict the strength of artificially designed promoter sequences. Our work provides a powerful platform that enables the predictable tuning of promoters to achieve the optimal transcriptional strength.

scholarly journals Model-driven generation of artificial yeast promoters

2019 ◽  
Author(s):  
Benjamin J. Kotopka ◽  
Christina D. Smolke
Keyword(s):  
Model Organism ◽  
Inducible Promoter ◽  
Design Strategies ◽  
Multiple Sequence ◽  
Promoter Sequences ◽  
Model Driven ◽  
Large Sets ◽  
Promoter Library ◽  
Small Set ◽  
Rapid Generation

AbstractPromoters play a central role in controlling gene regulation; however, a small set of promoters is used for most genetic construct design in the yeast Saccharomyces cerevisiae. Generating and utilizing models that accurately predict protein expression from promoter sequences would enable rapid generation of novel useful promoters and facilitate synthetic biology efforts in this model organism. We measured the gene expression activity of over 675,000 unique sequences in a constitutive promoter library, and over 327,000 sequences in an inducible promoter library. Training an ensemble of convolutional neural networks jointly on the two datasets enabled very high (R2 > 0.79) predictive accuracies on multiple sequence-activity prediction tasks. We developed model-guided design strategies which yielded large, sequence-diverse sets of novel promoters exhibiting activities similar to current best-in-class sequences. In addition to providing large sets of new promoters, our results show the value of model-guided design as an approach for generating useful DNA parts.

scholarly journals Assessing and characterising the repertoire of constitutive promoter elements in soil metagenomic libraries inEscherichia coli

2017 ◽  
Author(s):  
Cauã Antunes Westmann ◽  
Luana de Fátima Alves ◽  
Rafael Silva-Rocha ◽  
María-Eugenia Guazzaroni
Keyword(s):  
Metagenomic Library ◽  
Regulatory Elements ◽  
Regulatory Sequences ◽  
Functional Metagenomics ◽  
Promoter Elements ◽  
Transcriptional Regulatory Elements ◽  
Promoter Sequences ◽  
Metagenomic Libraries ◽  
Transcriptional Regulatory ◽  
The Relationship

SUMMARYAlthough functional metagenomics has been widely employed for the discovery of genes relevant to biotechnology and biomedicine, its potential for assessing the diversity of transcriptional regulatory elements of microbial communities has remained poorly explored. Here, we have developed a novel framework for prospecting, characterising and estimating the accessibility of promoter sequences in metagenomic libraries by combining a bi-directional reporter vector, high-throughput fluorescence assays and predictive computational methods. Using the expression profiling of fluorescent clones from two independent libraries from soil samples, we directly analysed the regulatory dynamics of novel promoter elements, addressing the relationship between the “metaconstitutome” of a bacterial community and its environmental context. Through the construction and screening of plasmid-based metagenomic libraries followed byin silicoanalyses, we were able to provide both (i) a consensus exogenous promoter elements recognizable byEscherichia coliand (ii) an estimation of the accessible promoter sequences in a metagenomic library, which was close to 1% of the whole set of available promoters. The results presented here should provide new directions for the exploration through functional metagenomics of novel regulatory sequences in bacteria, which could expand the Synthetic Biology toolbox for novel biotechnological and biomedical applications.

scholarly journals Mitochondrial Sirtuins in Reproduction

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1047
Author(s):  
Giovanna Di Emidio ◽  
Stefano Falone ◽  
Paolo Giovanni Artini ◽  
Fernanda Amicarelli ◽  
Anna Maria D’Alessandro ◽  
...  
Keyword(s):  
Stress Responses ◽  
Metabolic Pathways ◽  
Redox Balance ◽  
Antioxidant Defenses ◽  
Metabolic Abnormalities ◽  
Female Reproduction ◽  
Mitochondrial Dysfunctions ◽  
Early Embryos ◽  
The Relationship

Mitochondria act as hubs of numerous metabolic pathways. Mitochondrial dysfunctions contribute to altering the redox balance and predispose to aging and metabolic alterations. The sirtuin family is composed of seven members and three of them, SIRT3-5, are housed in mitochondria. They catalyze NAD+-dependent deacylation and the ADP-ribosylation of mitochondrial proteins, thereby modulating gene expression and activities of enzymes involved in oxidative metabolism and stress responses. In this context, mitochondrial sirtuins (mtSIRTs) act in synergistic or antagonistic manners to protect from aging and aging-related metabolic abnormalities. In this review, we focus on the role of mtSIRTs in the biological competence of reproductive cells, organs, and embryos. Most studies are focused on SIRT3 in female reproduction, providing evidence that SIRT3 improves the competence of oocytes in humans and animal models. Moreover, SIRT3 protects oocytes, early embryos, and ovaries against stress conditions. The relationship between derangement of SIRT3 signaling and the imbalance of ROS and antioxidant defenses in testes has also been demonstrated. Very little is known about SIRT4 and SIRT5 functions in the reproductive system. The final goal of this work is to understand whether sirtuin-based signaling may be taken into account as potential targets for therapeutic applications in female and male infertility.

Metabolism-driven post-translational modifications of H3K9 in early bovine embryos

Reproduction ◽  
2021 ◽  
Vol 162 (3) ◽  
pp. 181-191
Author(s):  
Jessica Ispada ◽  
Aldcejam Martins da Fonseca Junior ◽  
Otávio Luiz Ramos Santos ◽  
Camila Bruna de Lima ◽  
Erika Cristina dos Santos ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Developmental Stages ◽  
De Novo ◽  
Blastocyst Stage ◽  
Developmental Model ◽  
Bovine Embryos ◽  
Acetyl Coa ◽  
Post Translational Modifications ◽  
The Relationship ◽  
Different Levels

Metabolic and molecular profiles were reported as different for bovine embryos with distinct kinetics during the first cleavages. In this study, we used this same developmental model (fast vs slow) to determine if the relationship between metabolism and developmental kinetics affects the levels of acetylation or tri-methylation at histone H3 lysine 9 (H3K9ac and H3K9me3, respectively). Fast and slow developing embryos presented different levels of H3K9ac and H3K9me3 from the earliest stages of development (40 and 96 hpi) and up to the blastocyst stage. For H3K9me3, both groups of embryos presented a wave of demethylation and de novo methylation, although it was more pronounced in fast than slow embryos, resulting in blastocysts with higher levels of this mark. The H3K9ac reprogramming profile was distinct between kinetics groups. While slow embryos presented a wave of deacetylation, followed by an increase in this mark at the blastocyst stage, fast embryos reduced this mark throughout all the developmental stages studied. H3K9me3 differences corresponded to writer and eraser transcript levels, while H3K9ac patterns were explained by metabolism-related gene expression. To verify if metabolic differences could alter levels of H3K9ac, embryos were cultured with sodium-iodoacetate (IA) or dichloroacetate (DCA) to disrupt the glycolytic pathway or increase acetyl-CoA production, respectively. IA reduced H3K9ac while DCA increased H3K9ac in blastocysts. Concluding, H3K9me3 and H3K9ac patterns differ between embryos with different kinetics, the second one explained by metabolic pathways involved in acetyl-CoA production. So far, this is the first study demonstrating a relationship between metabolic differences and histone post-translational modifications in bovine embryos.

scholarly journals Dissecting the Microbial Community Structure of Internal Organs During the Early Postmortem Period in a Murine Corpse Model

2021 ◽  
Author(s):  
Ruina Liu ◽  
Kai Zhang ◽  
Huan Li ◽  
Qinru Sun ◽  
Xin Wei ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
The Body ◽  
Time Since Death ◽  
Limited Information ◽  
Microbial Composition ◽  
Internal Organs ◽  
Organ Specific ◽  
Forensic Microbiology ◽  
The Relationship ◽  
Early Postmortem

Abstract Background Microorganisms inhabit and proliferate throughout the body both externally and internally, which are the primary mediators of putrefaction after death. However, limited information is available about the changes in the postmortem microbiota of extraintestinal body sites in the early decomposition stage of mammalian corpses. Results This study applied 16S rRNA barcoding to investigate microbial composition variations among different organs and the relationship between microbial communities and time since death over 1 day of decomposition. During 1 day of decomposition, Agrobacterium, Prevotella, Bacillus, and Turicibacter were regarded as time-relevant genera in internal organs at different timepoints. Pathways associated with lipid, amino acid, carbohydrate and terpenoid and polyketide metabolism were significantly enriched at 8 hours than that at 0.5 or 4 hours. The microbiome compositions and postmortem metabolic pathways differed by time since death, and more importantly, these alterations were organ specific. Conclusion The dominant microbes differed by organ, while they tended toward similarity as decomposition progressed. The observed thanatomicrobiome variation by body site provides new knowledge into decomposition ecology and forensic microbiology. Additionally, the microbes detected at 0.5 hours in internal organs may inform a new direction for organ transplantation.

scholarly journals Transcription start site analysis reveals widespread divergent transcription in D. melanogaster and core promoter-encoded enhancer activities

2017 ◽  
Author(s):  
Sarah Rennie ◽  
Maria Dalby ◽  
Marta Lloret-Llinares ◽  
Stylianos Bakoulis ◽  
Christian Dalager Vaagensø ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Core Promoter ◽  
Regulatory Element ◽  
Regulatory Elements ◽  
Chromatin Interaction ◽  
Promoter Strength ◽  
Gene Promoters ◽  
Core Promoters ◽  
Promoter Architecture ◽  
Regulatory Functions

ABSTRACTMammalian gene promoters and enhancers share many properties. They are composed of a unified promoter architecture of divergent transcripton initiation and gene promoters may exhibit enhancer function. However, it is currently unclear how expression strength of a regulatory element relates to its enhancer strength and if the unifying architecture is conserved across Metazoa. Here we investigate the transcription initiation landscape and its associated RNA decay in D. melanogaster. Surprisingly, we find that the majority of active gene-distal enhancers and a considerable fraction of gene promoters are divergently transcribed. We observe quantitative relationships between enhancer potential, expression level and core promoter strength, providing an explanation for indirectly related histone modifications that are reflecting expression levels. Lowly abundant unstable RNAs initiated from weak core promoters are key characteristics of gene-distal developmental enhancers, while the housekeeping enhancer strengths of gene promoters reflect their expression strengths. The different layers of regulation mediated by gene-distal enhancers and gene promoters are also reflected in chromatin interaction data. Our results suggest a unified promoter architecture of many D. melanogaster regulatory elements, that is universal across Metazoa, whose regulatory functions seem to be related to their core promoter elements.

scholarly journals Function, Detection and Alteration of Acylcarnitine Metabolism in Hepatocellular Carcinoma

Metabolites ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 36 ◽  
Author(s):  
Shangfu Li ◽  
Dan Gao ◽  
Yuyang Jiang
Keyword(s):  
Hepatocellular Carcinoma ◽  
Metabolic Pathways ◽  
Poor Prognosis ◽  
Current Evidence ◽  
Long Chain Fatty Acids ◽  
Primary Malignancy ◽  
Diagnosis And Prognosis ◽  
Analytical Platforms ◽  
The Relationship ◽  
Long Chain

Acylcarnitines play an essential role in regulating the balance of intracellular sugar and lipid metabolism. They serve as carriers to transport activated long-chain fatty acids into mitochondria for β-oxidation as a major source of energy for cell activities. The liver is the most important organ for endogenous carnitine synthesis and metabolism. Hepatocellular carcinoma (HCC), a primary malignancy of the live with poor prognosis, may strongly influence the level of acylcarnitines. In this paper, the function, detection and alteration of acylcarnitine metabolism in HCC were briefly reviewed. An overview was provided to introduce the metabolic roles of acylcarnitines involved in fatty acid β-oxidation. Then different analytical platforms and methodologies were also briefly summarised. The relationship between HCC and acylcarnitine metabolism was described. Many of the studies reported that short, medium and long-chain acylcarnitines were altered in HCC patients. These findings presented current evidence in support of acylcarnitines as new candidate biomarkers for studies on the pathogenesis and development of HCC. Finally we discussed the challenges and perspectives of exploiting acylcarnitine metabolism and its related metabolic pathways as a target for HCC diagnosis and prognosis.

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