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Results for “Synthetic Biology”

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At least 721 records · Page 40Linked to original sources

bioRxiv2021

Meeting Measurement Precision Requirements for Effective Engineering of Genetic Regulatory Networks

Reliable, predictable engineering of cellular behavior is one of the key goals of synthetic biology. As the field matures, biological engineers will become increasingly reliant on computer models that allow for the rapid exploration of design space prior to the more costly construction and characterization of candidate designs. The efficacy of such models, however, depends on the accuracy of their predictions, the precision of the measurements used to parameterize the models, and the tolerance of biological devices for imperfections in modeling and measurement. To better understand this relationship, we have derived an Engineering Error Inequality that provides a quantitative mathematical bound on the relationship between predictability of results, model accuracy, measurement precision, and device characteristics. We apply this relation to estimate measurement precision requirements for engineering genetic regulatory networks given current model and device characteristics, recommending a target standard deviation of 1.5-fold. We then compare these requirements with the results of an interlaboratory study to validate that these requirements can be met via flow cytometry with matched instrument channels and an independent calibrant. Based on these results, we recommend a set of best practices for quality control of flow cytometry data and discuss how these might be extended to other measurement modalities and applied to support further development of genetic regulatory network engineering.

synthetic biology↗

bioRxiv2023

Controlled protein activities with viral proteases, antiviral peptides, and antiviral drugs

Chemical control of protein activity is a powerful tool for scientific study, synthetic biology, and cell therapy; however, for broad use, effective chemical inducer systems must minimally crosstalk with endogenous processes and exhibit desirable drug delivery properties. Accordingly, the drug-controllable proteolytic activity of hepatitis C cis-protease NS3 and its associated antiviral drugs have been used to regulate protein activity and gene modulation. These tools advantageously exploit non-eukaryotic/prokaryotic proteins and clinically approved inhibitors. Here we expand the toolkit by utilizing catalytically inactive NS3 protease as a high affinity binder to genetically encoded, antiviral peptides. Through our approach, we create NS3-peptide complexes that can be displaced by FDA-approved drugs to modulate transcription, cell signaling, split-protein complementation. With our developed system, we discover a new mechanism to allosterically regulate Cre recombinase. Allosteric Cre regulation with NS3 ligands enables orthogonal recombination tools in eukaryotic cells and functions in divergent organisms to control prokaryotic recombinase activity.

synthetic biology↗

bioRxiv2022

Divergent Directed Evolution of a TetR-type Repressor Towards Aromatic Molecules

Reprogramming cellular behaviour is one of the hallmarks of synthetic biology. To this end, prokaryotic allosteric transcription factors (aTF) have been repurposed as versatile tools for processing small molecule signals into cellular responses. Expanding the toolbox of aTFs that recognize new inducer molecules is of considerable interest in many applications. Here, we first establish a resorcinol responsive aTF-based biosensor in Escherichia coli using the TetR-family repressor RolR from Corynebacterium glutamicum. We then perform an iterative walk along the fitness landscape of RolR to identify new inducer specificities, namely catechol, methyl catechol, caffeic acid, protocatechuate, L-DOPA, and the tumour biomarker homovanillic acid. Finally, we demonstrate the versatility of these engineered aTFs by transplanting them into the model eukaryote Saccharomyces cerevisiae. This work provides a framework for efficient aTF engineering to expand ligand specificity towards novel molecules on laboratory timescales, which, more broadly, is invaluable across a wide range of applications such as protein and metabolic engineering, as well as point-of-care diagnostics.

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bioRxiv2025

PHYCUT: Scalable multiplex CRISPR/Cas9 editing forgenome engineering in the diatom Phaeodactylumtricornutum

Diatoms are globally significant microalgae that contribute [~] 20% of oxygen production and exhibit remarkable metabolic diversity. The marine diatom Phaeodactylum tricornutum has emerged as a promising synthetic biology platform for bioproduction of recombinant proteins, supported by a human-like N-linked glycosylation pathway. However, its (1,3)-linked core fucose is immunogenic in humans and thus limits biopharmaceutical applications. One hurdle to efficient genome engineering in P. tricornutum is the lack of a robust system for simultaneous CRISPR/Cas9 editing at multiple sites. To overcome this limitation, we develop PHYCUT (Phaeodactylum tricornutum Csy4-Cas9 multiplex tool), a versatile plasmid-based CRISPR/Cas9 system that uses the Csy4 endoribonuclease to process multi-guide RNA arrays. To highlight PHYCUT applications, we demonstrate multiplex editing of all three FucT genes responsible for (1,3) fucosylation in P. tricornutum, yielding strains with markedly reduced fucosylation of secreted proteins. PHYCUT enables facile, multiplexed genome engineering in diatoms and provides a foundation for humanizing the P. tricornutum glycosylation pathway to support next-generation algal biotechnology.

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bioRxiv2017

Modeling mechanical interactions in growing populations of rod-shaped bacteria

Advances in synthetic biology allow us to engineer bacterial collectives with pre-specified characteristics. However, the behavior of these collectives is difficult to understand, as cellular growth and division as well as extra-cellular fluid flow lead to complex, changing arrangements of cells within the population. To rationally engineer and control the behavior of cell collectives we need theoretical and computational tools to understand their emergent spatiotemporal dynamics. Here, we present an agent-based model that allows growing cells to detect and respond to mechanical interactions. Crucially, our model couples the dynamics of cell growth to the cells environment: Mechanical constraints can affect cellular growth rate and a cell may alter its behavior in response to these constraints. This coupling links the mechanical forces that influence cell growth and emergent behaviors in cell assemblies. We illustrate our approach by showing how mechanical interactions can impact the dynamics of bacterial collectives growing in microfluidic traps.

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bioRxiv2024

SubtiToolKit - a bioengineering kit for Bacillus subtilis and Gram-positive bacteria.

Building DNA constructs of increasing complexity is key to synthetic biology. Golden Gate methods led to the creation of cloning toolkits - collections of modular standardized DNA parts hosted on hierarchic plasmids, developed for yeast, plants, Gram-negative bacteria, and human cells. However, Gram-positive bacteria have been neglected. Bacillus subtilis is a Gram-positive model organism and a workhorse in the bioindustry. Here, we present the SubtiToolKit, a high- efficiency cloning toolkit for B. subtilis and Gram-positive bacteria. Its design permits DNA constructs for transcriptional units, operons, knock-in and knock-out applications. It contains libraries of promoters, RBSs, fluorescent proteins, protein tags, terminators, genome integration parts, a no-leakage genetic device to control the expression of toxic products during E. coli assembly, and a toolbox for industrially relevant strains of Geobacillus and Parageobacillus as an example of SubtiToolKit versatility for other Gram-positive bacteria and its future perspective as a reference toolkit.

synthetic biology↗

bioRxiv2021

Construction of multicellular yeast networks using the communication toolkit with variable specificity and attenuation

The key next step in synthetic biology is to extend cellular network engineering to the multicellular level by utilizing cell-cell communication for information processing. To facilitate the implementation of multicellular networks in the most commonly used eukaryotic chassis, Saccharomyces cerevisiae, we developed the yeast communication toolkit (YCTK). This toolkit is based on the fungal mating pathway and contains five pheromone-inducible promoters (response parts), eleven pheromones (-factors; sender parts), eleven pheromone receptors (Ste2; receiver parts), as well as five Bar1 proteases (suppressor parts). All YCTK parts were thoroughly characterized and are compatible with the commonly used yeast Golden Gate cloning standard. We demonstrated the application of the YCTK by implementing several different logic gate-like population networks. Furthermore, we used this toolkit to investigate the pheromone-receptor promiscuity patterns among different yeast species. This toolkit extends currently available resources for construction of complex multicellular eukaryotic networks with varying degrees of promiscuity and attenuation.

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bioRxiv2020

Engineering E. coli for magnetic control and the spatial localization of functions

The fast-developing field of synthetic biology enables broad applications of programmed microorganisms including the development of whole-cell biosensors, delivery vehicles for therapeutics, or diagnostic agents. However, the lack of spatial control required for localizing microbial functions could limit their use and induce their dilution leading to ineffective action or dissemination. To overcome this limitation, the integration of magnetic properties into living systems enables a contact-less and orthogonal method for spatiotemporal control. Here, we generated a magnetic-sensing Escherichia coli by driving the formation of iron-rich bodies into bacteria. We found that these bacteria could be spatially controlled by magnetic forces and sustained cell growth and division, by transmitting asymmetrically their magnetic properties to one daughter cell. We combined the spatial control of bacteria with genetically encoded-adhesion properties to achieve the magnetic capture of specific target bacteria as well as the spatial modulation of human cell invasions.

synthetic biology↗

bioRxiv2017

Deep learning of the regulatory grammar of yeast 5’ untranslated regions from 500,000 random sequences

Our ability to predict protein expression from DNA sequence alone remains poor, reflecting our limited understanding of cis-regulatory grammar and hampering the design of engineered genes for synthetic biology applications. Here, we generate a model that predicts the translational efficiency of the 5 untranslated region (UTR) of mRNAs in the yeast Saccharomyces cerevisiae. We constructed a library of half a million 50-nucleotide-long random 5 UTRs and assayed their activity in a massively parallel growth selection experiment. The resulting data allow us to quantify the impact on translation of Kozak sequence composition, upstream open reading frames (uORFs) and secondary structure. We trained a convolutional neural network (CNN) on the random library and showed that it performs well at predicting the translational efficiency of both a held-out set of the random 5 UTRs as well as native S. cerevisiae 5 UTRs. The model additionally was used to computationally evolve highly translating 5 UTRs. We confirmed experimentally that the great majority of the evolved sequences lead to higher translation rates than the starting sequences, demonstrating the predictive power of this model.

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bioRxiv2021

Improving genomically recoded Escherichia coli for the production of proteins containing non-canonical amino acids

A genomically recoded Escherichia coli strain that lacks all amber codons and release factor 1 (C321.{Delta}A) enables efficient genetic encoding of chemically diverse, non-canonical amino acids (ncAAs) into proteins. While C321.{Delta}A has opened new opportunities in chemical and synthetic biology, this strain has not been optimized for protein production, limiting its utility in widespread industrial and academic applications. To address this limitation, we describe the construction of a series of genomically recoded organisms that are optimized for cellular protein production. We demonstrate that the functional deactivation of nucleases (e.g., rne, endA) and proteases (e.g., lon) increases production of wild-type superfolder green fluorescent protein (sfGFP) and sfGFP containing two ncAAs up to [~]5-fold. Additionally, we introduce a genomic IPTG-inducible T7 RNA polymerase (T7RNAP) cassette into these strains. Using an optimized platform, we demonstrated the ability to introduce 2 identical N6-(propargyloxycarbonyl)-L-Lysine residues site specifically into sfGFP with a 17-fold improvement in production relative to the parent. We envision that our library of organisms will provide the community with multiple options for increased expression of proteins with new and diverse chemistries.

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bioRxiv2024

Semi-automated workflow for high-throughput Agrobacterium-mediated plant transformation

High-throughput experiments in plants are hindered by long generation times and high costs. To address these challenges, we present an optimized pipeline for Agrobacterium tumefaciens transformation and simplified a protocol to obtain stable transgenic lines of the model liverwort Marchantia polymorpha, paving the way for efficient high-throughput experiments for plant synthetic biology and other applications. Our protocol involves freeze-thaw Agrobacterium transformation method in 6-well plates that can be adapted to robotic automation. Using the Opentrons open-source platform, we implemented a semi-automated protocol showing similar efficiency compared to manual manipulation. Additionally, we have streamlined and simplified the process of stable transformation and selection of M. polymorpha, reducing cost, time, and manual labour without compromising transformation efficiency. The addition of sucrose in the selection media significantly enhances the production of gemmae, accelerating the generation of isogenic plants. We believe these protocols have the potential to facilitate high-throughput screenings in diverse plant species and represent a significant step towards the full automation of plant transformation pipelines. This approach allows testing [~]100 constructs per month, using conventional plant tissue culture facilities. We recently demonstrated the successful implementation of this protocol for screening hundreds of fluorescent reporters in Marchantia gemmae.

synthetic biology↗

bioRxiv2021

Combinatorial engineering of bulk-assembled monodisperse coacervate droplets towards logically integrated protocells

Bottom-up synthetic biology seeks to construct artificial cells from simple building blocks for exploring origin and principles of cellular life and material design. Although cellular life may have emerged spontaneously, programmable integration of building blocks into size, membrane property-controlled compartments (liposome or coacervate) towards cellular organization, without using specialized devices, has proven difficult. Here, we report a self-templated route to monodisperse complex droplets in bulk solution from coacervate-liposome synergy, with nanoliposome controlling coacervate size and coacervate templating on-surface nanoliposome fusion. Nanoliposome-coated monodisperse coacervates are self-assembled within 30 seconds, which are sealed by fusing nanoliposomes into size-controlled giant unilamellar vesicles (GUVs), with model building blocks combinatorially integrated into droplets. Defect-free membrane is established on coacervate, which render these complex GUVs surviving at extreme osmotic, salty and pH conditions (4 M NaCl, 100 mM HCl, 1 M NaOH), while providing homeostasis for enzymatic reactions, reminiscent of extremophiles.

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bioRxiv2023

A Flexible Transgene Integration Landing-Pad Toolkit in Human Induced Pluripotent Stem Cells Enables Facile Cellular Engineering, Gene Zygosity Control, and Parallel Transgene Integration

Development of a repeatable method for delivering transgene payloads to human induced pluripotent stem cells (hiPSCs) without risking unintended off-target effects is not fully realized. Yet, such methods are indispensable to fully unlocking the potential for applying synthetic biological approaches to regenerative medicine, delivering quantum impacts to cell-based therapeutics development. Here we present a toolkit for engineering hiPSCs centred on the development of two core landing-pad cell-lines, facilitating rapid high-efficiency delivery of transgenes to the AAVS1 safe-harbour locus using the Bxb1 large-serine recombinase. We developed two landing-pad cell lines expressing green and red fluorescent reporters respectively, both retaining stemness whilst fully capable of differentiation into all three germ layers. A fully selected hiPSC population can be isolated within 1-2 weeks after landing-pad recombinase-mediated cassette exchange. We demonstrate the capability for investigator-controlled homozygous or heterozygous transgene configurations in these cells. As such, the toolkit of vectors and protocols associated with this landing-pad hiPSC system has the potential to accelerate engineering workflows for researchers in a variety of disciplines.

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bioRxiv2023

Optogenetic spatial patterning of cooperation in yeast populations

Microbial communities are a siege of complex metabolic interactions such as cooperation and competition for resources. Methods to control such interactions could lead to major advances in our ability to engineer microbial consortia for bioproduction and synthetic biology applications. Here, we used optogenetics to control invertase production in yeast, thereby creating landscapes of cooperator and cheater cells. Yeast cells behave as cooperators (i.e., transform sucrose into glucose, a public "good") upon blue light illumination or cheaters (i.e., consume glucose produced by cooperators to grow) in the dark. We show that cooperators benefit best from the hexoses they produce when their domain size is constrained between two cut-off length-scales. From an engineering point of view, the system behaves as a band pass filter. The lower limit is the trace of cheaters competition for hexoses, while the upper limit is defined by cooperators competition for sucrose. Hence, cooperation mostly occurs at the frontiers with cheater cells, which not only compete for hexoses but also cooperate passively by letting sucrose reach cooperators. We anticipate that this optogenetic method could be applied to shape metabolic interactions in a variety of microbial ecosystems.

synthetic biology↗

bioRxiv2018

Cooperation Enhances Robustness of Coexistence in Spatially Structured Consortia

Designing synthetic microbial consortia is an emerging area in synthetic biology and a major goal is to realize stable and robust coexistence of multiple species. Co-operation and competition are fundamental intra/interspecies interactions that shape population level behaviors, yet it is not well-understood how these interactions affect the stability and robustness of coexistence. In this paper, we show that communities with cooperative interactions are more robust to population disturbance, e.g., depletion by antibiotics, by forming intermixed spatial patterns. Meanwhile, competition leads to population spatial heterogeneity and more fragile coexistence in communities. Using reaction-diffusion and nonlocal PDE models and simulations of a two-species E. coli consortium, we demonstrate that cooperation is more beneficial than competition in maintaining coexistence in spatially structured consortia, but not in well-mixed environments. This also suggests a trade-off between constructing heterogeneous communities with localized functions and maintaining robust coexistence. The results provide general strategies for engineering spatially structured consortia by designing interspecies interactions and suggest the importance of cooperation for biodiversity in microbial community.

synthetic biology↗

bioRxiv2017

Computational design of Small Transcription Activating RNAs (STARs) for versatile and dynamic gene regulation

A longstanding goal of synthetic biology has been the programmable control of cellular functions. Central to this goal is the creation of versatile regulatory toolsets that allow for programmable control of gene expression. Of the many regulatory molecules available, RNA regulators offer the intriguing possibility of de novo design - allowing for the bottom-up molecular-level design of genetic control systems. Here we present a computational design approach for the creation of a bacterial regulator called Small Transcription Activating RNAs (STARs) and create a library of high-performing and orthogonal STARs that achieve up to [~]9000-fold gene activation. We then demonstrate the versatility of RNA-based transcription control by showing the broad utility of STARs - from acting synergistically with existing constitutive and inducible regulators, to reprogramming cellular phenotypes and controlling multigene metabolic pathway expression. Finally, we combine these new STARs with themselves and CRISPRi transcriptional repressors to deliver new types of RNA-based genetic circuitry that allow for sophisticated and temporal control of gene expression.

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bioRxiv2021

Multiplexed Cell-Based Diagnostic Devices for Detection of Renal Biomarkers Using Genetic Circuits

The number of synthetic biology based solutions employed in the medical industry is growing every year. The whole cell biosensors being one of them, have been proven valuable tools for developing low-cost, portable, personalized medicine alternatives to conventional techniques. Based on this concept, we targeted one of the major health problems in the world, Chronic Kidney Disease (CKD). To do so, we developed two novel biosensors for the detection of two important renal biomarkers; urea and uric acid. Using advanced gene expression control strategies we improved the operational range and the response profiles of each biosensor to meet clinical specifications. We further engineered these systems to enable multiplexed detection as well as an AND-logic gate operating system. Finally, we tested the applicability of these systems and optimized their working dynamics inside complex medium human blood serum. This study could help the efforts to transition from labor-intensive and expensive laboratory techniques to widely available, portable, low cost diagnostic options.

synthetic biology↗

bioRxiv2024

Risk-averse optimization of genetic circuits under uncertainty

Synthetic biology aims to engineer biological systems with specified functions. This requires navigating an extensive design space, which is challenging to achieve with wet lab experiments alone. To expedite the design process, mathematical modelling is typically employed to predict circuit function in silico ahead of implementation, which when coupled with computational optimization can be used to automatically identify promising designs. However, circuit models are inherently inaccurate which can result in sub-optimal or non-functional in vivo performance. To mitigate this issue, here we propose to combine Bayesian inference, Thompson sampling, and risk management to find optimal circuit designs. Our approach employs data from non-functional designs to estimate the distribution of the model parameters and then employs risk-averse optimization to select design parameters that are expected to perform well given parameter uncertainty and biomolecular noise. We illustrate the approach by designing robust adaptation circuits and genetic oscillators with a prescribed frequency. The proposed approach provides a novel methodology for the design of robust genetic circuitry.

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