Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/656223

A reversible memory switch for plant synthetic biology based on the phage PhiC31 integration system

Bernabe-Orts, J. M.·Quijano-Rubio, A.·Mancheno-Bonillo, J.·Moles-Casas, V.·Selma, S.·Granell, A.·Orzaez, D.
View original source ↗Export metadata ↓

Abstract

Plant synthetic biology aims to contribute to global food security by engineering plants with new or improved functionalities. In recent years, synthetic biology has rapidly advanced from the setup of basic genetic devices to the design of increasingly complex gene circuits able to provide organisms with novel functions. While many bacterial, fungal and mammalian unicellular chassis have been extensively engineered, this progress has been delayed in plants due to their complex multicellular nature and the lack of reliable DNA devices that allow an accurate design of more sophisticated biological circuits. Among these basic devices, gene switches are crucial to deploying new layers of regulation into the engineered organisms. Of special interest are bistable genetic toggle switches, which allow a living organism to exist in two alternative states and switch between them with a minimal metabolic burden. Naturally occurring toggle switches control important decision-making processes such as cell fate and developmental events. We sought to engineer whole plants with an orthogonal genetic toggle switch to be able to regulate artificial functions with minimal interference with their natural pathways. Here we report a bistable toggle memory switch for whole plants based on the phage PhiC31 serine integrase and its cognate recombination directionality factor (RDF). This genetic device was designed to control the transcription of two genes of interest by inversion of a central DNA regulatory element. Each state of the device is defined by one transcriptionally active gene of interest, while the other one remains inactive. The state of the switch can be reversibly modified by the action of the recombination actuators, which were administered externally (e.g. via agroinfiltration), or produced internally in response to an inducible chemical stimulus. We extensively characterized the kinetics, memory, and reversibility of this genetic switch in Nicotiana benthamiana through transient and stable transformation experiments using transgenic plants and hairy roots. Finally, we coupled the integrase expression to an estradiol-inducible promoter as a proof of principle of inducible activation of the switch.

Source connections

Explore related subjects

synthetic biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bernabe-Orts, J. M., Quijano-Rubio, A., Mancheno-Bonillo, J., Moles-Casas, V., Selma, S., Granell, A., Orzaez, D.. 2019-05-31. A reversible memory switch for plant synthetic biology based on the phage PhiC31 integration system. https://doi.org/10.1101/656223

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Creation of genomic chimeras via megabase scale genome expansion

An organism's physiology is controlled by its genomic content. Building genomic chimeras would enable melding of the diverse functions and properties of life. However, prior arts in genome synthesis are limited to reconstituting pre-existing functions within a singular genome rather than combining diverse genomic functions across multiple distinct genomes. Existing methods are also prohibitively expensive, labor intensive, and time consuming, and thus fundamentally not scalable for creating large synthetic chimeric genomes. To address all these limitations, we invented Additive Conjugative-CAST Engineering (ACE) combining conjugation with CRISPR-associated transposition (CAST) to deliver and integrate up to half a genome per step from a donor cell into a precisely defined position in the recipient's genome. We have demonstrated ACE's capability to integrate at least a 2-megabase donor genomic segment in a single step and at least 3 megabase in two consecutive steps. Importantly, we confirmed ACE's generality through the creation of multiple genomic chimeras across species, genus, and at least order barriers. With ACE, we further demonstrate such chimeric organisms, or what we call genome expanded organisms (GEOs), can be stably forged from at least three starting bacterial strains, and can be stably maintained to express all their acquired genomic parts in a single chimera. ACE offers a new paradigm of creating artificial lifeforms to combine desired properties and potentially create novel functions beyond the constraints of nature. ACE also offers a unique perspective to probe unexplored plasticity in genome architecture and expression patterns of novel, massively expanded genomes.

synthetic biology↗
bioRxiv2026

Functional analysis of small-molecule and protein binding domains using monomeric streptavidin-based two-component biosensors

Protein biosensors are important analytical and diagnostic tools that convert molecular recognition into measurable activity. Most common two-component biosensors require two non-competing recognition domains, yet binding affinity and specificity alone do not reliably predict their compatibility with the rest of the biosensor. We report a modular platform that exploits monomeric streptavidin (mSA2) as a surrogate recognition domain, enabling rapid functional evaluation of candidate binders in the context of biosensor scaffold without requiring a second ligand-specific binding protein. We established a chromatography-free protocol for recovering functional mSA2-based biosensor components from Escherichia coli. Using biotinylated small molecules methotrexate and vitamin D3, as well as heart failure protein biomarkers galectin-3 and S100A7 we demonstrate ligand-dependent reporter biosensor activation. The developed platform provides a scalable approach for rapid binder evaluation and biosensor prototyping, streamlining biosensor development using binding domains generated by directed evolution or computational protein design.

synthetic biology↗
bioRxiv2026

Developing synthetic auxin-based trans-kingdom signaling

Synthetic trans-kingdom signaling systems with tunable transduction properties provide a unique avenue to explore how communication between organisms coordinate behaviors without the confounding complexity of natural systems. However, existing trans-kingdom signaling systems suffer from either toxic signal molecules, a need for rare precursors for signal generation, or transduction machinery which is either species-specific or cannot be easily tuned. This limits their capacity to be broadly applied across kingdoms and their utility as a model system to study trans-kingdom interactions. In this work we elucidate the design principles for a trans-kingdom signaling system based on the plant phytohormone, Indole 3-Acetic Acid (auxin), that overcomes these challenges. We demonstrate how auxin biosynthesis can be engineered into a model sender organism, the cyanobacteria Synechococcus elongatus PCC 7942, and how this signal can be tuned with low leak and high dynamic range. We also show these signals can be connected to gene expression using tunable synthetic auxin-responsive signaling systems across multiple kingdoms. We demonstrate that S. elongatus generated auxin signals can tune gene expression in co-cultured Saccharomyces cerevisiae via auxin-induced degradation. Additionally, we show that when the S. elongatus are associated with the roots of the model plant, Arabidopsis thaliana, the auxin they generate can control gene expression via auxin-responsive synthetic transcription factors expressed from the plants genome. Taken together, our results demonstrate the design principles for a tunable auxin-based trans-kingdom signaling system that can be broadly applied across species.

synthetic biology↗