Qr: switch:"Magnets"
Showing 1 - 25 of 198 results
1.
Dimer asymmetry in signaling of blue light sensor histidine kinases.
Abstract:
Photoreceptor sensory histidine kinases (SHKs) couple light absorption to conformational changes regulating two-component signaling. Despite their importance and widespread use in optogenetics, the underlying structural signaling mechanisms remain poorly understood. Here, we engineered dimeric SHKs based on Pseudomonas putida short light-oxygen-voltage (LOV) proteins, determined their crystal structures, and investigated their signaling mechanisms. Regardless of illumination, the structures adopted a light-state like LOV-LOV dimer with symmetric/straight kinase modules. In contrast, small-angle x-ray scattering together with functional assays revealed pronounced light-dependent rearrangements in solution and allowed the assignment of the kinase-ON dark state to an asymmetric/kinked conformation, whereas the light state adopts a symmetric/straight structure. Comparative analyses of natural and engineered SHKs identified conserved motifs linking light-induced LOV domain rotation to kinase activity. The findings highlight the central role of dimer asymmetry and flexibility in SHK signaling, thereby not least informing the engineering of new light-responsive signaling systems.
2.
Light-controlled CRISPR-dCas9 epigenome editing: advanced drug-delivery strategies and oncology applications.
Abstract:
Cancer is increasingly recognized as a disease of the dysregulated epigenome; however, current epi-drugs are blunt, systemically toxic instruments. Catalytically dead CRISPR nucleases (dCas9) linked to chromatin effectors have now made it possible not only to write and erase epigenetic marks at specified loci without double-strand breaks but also to add an element of optogenetics, or reversible and light-encoded control over the timing and localization of the editors. In this review, the technological underpinnings of light-controlled CRISPR-dCas9 epigenome editing, which include architectures of dCas9 scaffold and guide, blue-to-near-infrared photoswitches, and high-gain epigenetic effector designs, are synthesized, and viral, non-viral, and stimuli-responsive delivery platforms, which have to be co-optimized with clinical light interfaces, are discussed. We then outline four functional routes by which opto-epigenome editors may be used therapeutically in cancer: tumor suppressor reactivation; oncogene and super-enhancer repression with metabolic rewiring; control of cancer stem cell differentiation; and immunomodulation of the tumor microenvironment. Lastly, a translational roadmap is defined in terms of preclinical model tiers, biomarker strategies, regulatory and manufacturing factors, and future directions, including NIR and bioluminescent actuation, implantable μLED devices, and AI-guided closed-loop illumination. Together, these aspects constitute design principles for advancing light-addressable epigenome editors toward first-in-human studies and for integrating them into combination regimens as a new class of precision cancer therapeutics.
3.
Design and Implementation of a Blue-Light-Controlled Gene-Switch System.
Abstract:
Synthetic biology seeks to build predictable, programmable biological systems. We developed a blue-light-inducible T7RNAP system with dual-input regulation to enable precise spatiotemporal gene control, which is vital for biomanufacturing, therapy, and microbial engineering. We optimized it by replacing RBS sequences, testing tandem T7 promoters, and evaluating split-T7RNAP variants. Expression and bactericidal efficacy were assessed via fluorescent output and real-time growth curves under blue light. RBS variants caused up to 50-fold differences in expression. Three tandem T7 promoters provided the best balance between yield and fidelity. Integration of a benzoate-responsive module enabled 4.5-fold repression at 3 mM benzoate, demonstrating effective chemical off-switching without compromising light induction. This system combines blue light precision with environmental responsiveness, offering non-invasive, on-demand activation for antimicrobial therapy or spatial bioproduction. The benzoate-triggered off-switch is especially valuable for ecological applications such as biocontainment or bioremediation, where gene expression must shut down upon detection of pollutants, for example, aromatic hydrocarbons. Its orthogonal, modular design supports context-dependent control, making it ideal for environmental biosensors, programmable probiotics, and smart antimicrobial delivery in complex ecosystems.
4.
Inducible CRISPR/Cas systems in precision oncology: Current applications and future perspectives.
Abstract:
Inducible CRISPR/Cas systems enable spatiotemporal control of genome editing in response to chemical, optical, biological, or physical stimuli. By restricting genome-editing activity to defined conditions, these systems may reduce off-target exposure and immune burden while improving tumor-selective control, making them attractive tools for precision oncology.
5.
Advanced strategies to enhance the safety, persistence, and efficacy of CAR-T cells in solid tumors.
Abstract:
Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of hematologic cancers but encounters challenges, including severe treatment-related toxicities, a highly suppressive tumor microenvironment (TME), limited long-term persistence, and poor trafficking/infiltration into solid tumors. This review outlines recent genetic engineering strategies to address these issues and enhance the safety, durability, and efficacy of CAR-T cell therapy. To reduce cytokine release syndrome and neurotoxicity, methods such as affinity-tuned and humanized scFvs, hinge/TM optimization, and ITAM calibration have been developed, along with programmable "switch-off" and "switch-on" systems that include suicide genes, antibody-bridging switches, and optogenetic or hypoxia-gated circuits. TME remodeling strategies utilize nanomaterials for targeted cytokine delivery, cell-surface "backpack" systems, and engineered oncolytic viruses that release cytokines or checkpoint-blocking agents. For durability and resistance to exhaustion, precise genome engineering techniques, including CRISPR-based editing and multiplexed shRNA platforms, were employed to target inhibitory receptors and exhaustion-driving transcriptional programs. Additionally, chemokine-receptor engineering and local biomaterial-based delivery systems are discussed as ways to enhance CAR-T trafficking and intratumoral persistence. These innovations collectively point toward integrated, patient-specific CAR-T platforms that incorporate safety controls, metabolic and transcriptional flexibility, and enhanced trafficking through the TME to broaden clinical use.
6.
A non-invasive method for light-inducible knockout across all cell types in mouse subcutaneous adipose tissue.
Abstract:
Cre recombination is a widely used technique for mechanistic insights in physiology and disease. However, available constitutive and inducible Cre systems present challenges that can be prohibitive for some study designs. For example, Cre expression can result in cell types targeted across numerous tissues and organs, or when a gene is expressed across multiple cell types in a tissue, Cre-Lox restricted knockout will not enable ablation across an entire tissue or organ. Photoactivatable Cre (PA-Cre) systems enable temporally and spatially restricted gene expression control in delimited anatomical regions, typically requiring a micro-LED or fibre optic implantation. Here, we report as proof-of-concept the effective knockout of BDNF in subcutaneous adipose tissue after PA-Cre activation through external blue light illumination in awake, freely moving mice. We demonstrated that for mice with black fur, shaving can be used to anatomically limit PA-Cre activation. BDNF protein expression was decreased by 87% in the inguinal scWAT after blue light exposure, with no effect observed in the perigonadal (deep) or axillary subcutaneous (non-shaved) adipose tissues. We propose blue light induction of PA-Cre as safe and effective to study adipose tissue physiology and pathology across models. Considerations for applying this tool to future studies are also presented.
7.
Engineering an Optogenetic pH-Modulator in Bacteria.
Abstract:
Cells in many naturally occurring organisms routinely cooperate to control their extracellular pH in a dynamic and reversible manner, but this capability has been underexplored in synthetic biology. Here, we sought to engineer a microbial system that switches between two states -high and low extracellular pH- with minimal human intervention. We accomplished this by combining: (1) a genetic circuit that produces recombinant urease under the control of a light-inducible promoter; (2) a degradation tag on urease to accelerate the high-to-low pH transition; and (3) optimization of several environmental factors, including media composition, replenishment rate, and light exposure patterns. The system raises the pH when urease is produced and hydrolyzes urea in the media to produce ammonia; it lowers the pH as a byproduct of the cell's native metabolism when urease production ceases. We demonstrate that the optimized system cycles continuously for up to 14 days with minimal performance loss. Overall, our system demonstrates synthetic pH control in an engineered living system and highlights challenges and potential solutions for using such systems outside of the context of typical laboratory manipulation.
8.
An extracellular, optogenetic antibody platform for stimulus-gated antigen recognition and modulation of cell behavior.
Abstract:
Here, we present extrabody, an activatable, modular antibody platform that enables optogenetic or chemical reassembly of split antibody fragments for inducible extracellular antigen recognition. We demonstrate compatibility across diverse targets, including GFP, mCherry, and the tumor-associated antigens EGFR and HER2, and show that both nanobody- and scFv-derived fragments support light-dependent reconstitution. Extrabody enables input-gated cell-cell interactions and antigen transfer, providing external control over intercellular communication. Integration with synNotch receptors and chimeric antigen receptors (CARs) further allows dual-input regulation of downstream responses, including gene expression, cytokine release, and cytotoxicity. Together, these results establish extrabody as a versatile and generalizable interface for externally controlled cellular communication and synthetic signaling.
9.
Optimized optogenetic anti-CRISPR for endogenous gene regulation in Drosophila.
Abstract:
Optogenetic tools-light-responsive proteins that enable to regulate specific cellular activities, study biological processes, and develop new therapies-are attractive approaches for achieving endogenous gene regulation under minimally invasive conditions. Our first step in constructing an optogenetic system to regulate endogenous Drosophila gene expression was to identify inhibitory anti-CRISPR (Acr) proteins that block CRISPRa-mediated activation. Next, we inserted optogenetic protein LOV2 into these Acrs, tested for their ability to optogenetically modulate endogenous gene upregulation through the CRISPRa-based flySAM system in Drosophila, and found that the photoswitchability of these prototypes was weak. We therefore engineered an optimized Acr-LOV2 fusion module by refining length of intrinsically disordered and ordered regions (IDR and IOR) of Acrs. This optimization yielded a variant with significantly greater sensitivity to blue-light-induced endogenous gene upregulation than the prototypes, leading to new in vivo discoveries. In addition, this work provides insights for in vivo functional characterization of the IDR and the IOR of these small-sized proteins. Together, these findings establish a robust optogenetic toolbox for precise, light-controlled endogenous gene regulation in Drosophila.
10.
Illuminating cancer therapy: The translational path of optogenetics.
Abstract:
Tumor recurrence, metastasis, and therapeutic resistance remain major challenges in oncology, driving the need for advanced therapeutic strategies with improved precision and controllability. Optogenetics, which enables light-mediated regulation of cellular functions, has emerged as a promising modality for cancer therapy by offering unparalleled spatiotemporal precision. This capability allows dynamic control of intracellular signaling and transgene expression, enabling selective targeting of malignant cells while minimizing damage to surrounding tissues. However, clinical translation is hindered by key challenges, including inefficient in vivo delivery of optogenetic components, limited tissue penetration of activating light, and suboptimal performance of existing tools. Addressing these barriers requires a convergence of molecular engineering and materials science, wherein advanced biomaterials play a critical role in enabling gene delivery and overcoming tissue-penetration limitations in complex tumor environments. In this review, we provide a comprehensive oriented overview of optogenetics in oncology. We first analyze the molecular mechanisms and engineering principles of representative optogenetic tools, with a focus on LOV- and CRY2-based systems. We then highlight recent advances in biomaterial-assisted optogene delivery and light delivery strategies, emphasizing their material-dependent mechanisms that enable precise spatiotemporal control in vivo. Furthermore, we summarize emerging preclinical applications in cancer immunotherapy, gene regulation, and intracellular signaling control. Finally, we discuss key challenges in biosafety, kinetic optimization, and clinical scalability, and outline future directions that integrate optogenetics with functional materials and intelligent design to realize clinically viable platforms. This review aims to provide a framework for the development of clinically viable optogenetic platforms for next-generation cancer therapy.
11.
Light-inducible FLPase reconstitution enables temporal control of gene expression in Drosophila melanogaster.
Abstract:
Precise temporal control of gene expression is a prerequisite for disentangling timing-specific effects of gene function within the life cycle of Drosophila melanogaster. Here, we implement light-inducible FLPase reconstitution (LIFR) as a conditional gene expression system in flies, which combines blue light-responsive Magnet photoswitches and split-FLPase to remove an FRT-flanked stop cassette and irreversibly switch on transgene expression in response to light. This system is highly efficient, has virtually no transgene leakage, and a single light pulse is sufficient to induce long-term transgene expression. We demonstrate that LIFR in adulthood overcomes the developmental lethality elicited by constitutive pan-neuronal overexpression of neurodegeneration-causing mutants TDP43G298S and HTTQ97. We also illustrate that LIFR can help trace specific cell-type fates across developmental stages. Thus, we demonstrate proof of principle that LIFR is a versatile platform to conditionally activate long-lasting gene expression without the side effects of existing systems, thereby extending the Drosophila melanogaster genetic toolbox.
12.
Rationally designed light-inducible RNA-releasing protein for translational regulation and optogenetic control of gene therapies.
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Li, S
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Gao, T
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Wang, Y
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He, Q
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Ma, H
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Ye, H
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Shen, Y
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Wang, Y
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Wang, Y
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Li, X
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Fang, S
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Chen, Q
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Liu, Q
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Sun, G
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Xin, H
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Xue, J
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Liu, S
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Zhu, M
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Xu, W
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Wang, Z
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Shao, J
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Xie, M
Abstract:
In this study, we describe a rationally designed light-inducible RNA-releasing protein (LIRP) capable of inhibiting mRNA translation in the dark while permitting gene expression upon exposure to blue or ambient light. This LIRP-dependent gene switch is compatible with various delivery routes of gene- and cell-based therapy, such as subcutaneous implantation of microencapsulated light-sensitive cells or expression in various light-accessible body sites using single adeno-associated virus (AAV) vectors. To exemplify a gene therapy approach that directly harnesses ambient light as a natural illumination source to induce therapeutic action, we show how intradermal delivery of AAV2 vectors carrying a LIRP-regulated gene switch controlling murine thymic stromal lymphopoietin expression was effective in enabling light-dependent prevention and treatment of diet-induced obesity. To describe another therapeutic scenario, we engineered AAV2 vectors for LIRP-dependent expression of Vascular endothelial growth factor (VEGF) inhibitors for the treatment of retinal neovascular diseases. Upon intravitreal delivery into mice suffering from wet macular degeneration, VEGF inhibitors were constantly produced when animals were exposed to daylight, but therapeutic actions could be flexibly interrupted either by exposure to dark environments or by administration of a selective blue light filter at any point in time. When compared to conventional treatment strategies based on constitutive VEGF inhibition over the course of 3 months, we show that a regulated gene therapy approach through LIRP-dependent optogenetics was advantageous in maintaining a normal retina thickness. This work not only provides a valuable addition to the optogenetic toolbox but also offers a perspective to translate light-dependent gene switches toward therapeutic usage.
13.
Optogenetic Tools for Spatiotemporal Interrogation of Cytoskeletal Dynamics.
Abstract:
The cytoskeleton is a dynamic intracellular network that governs cell shape, migration, division, and mechanotransduction. Precise spatiotemporal control of cytoskeletal regulation is essential for understanding how these processes are coordinated in physiology and disease, yet conventional pharmacological and genetic approaches often lack sufficient resolution or reversibility. Optogenetic technologies provide a powerful alternative by enabling light-controlled, noninvasive manipulation of cytoskeletal regulators with high temporal precision and subcellular specificity. This review summarizes recent advances in genetically encoded optogenetic tools for interrogating cytoskeletal dynamics. We discuss core design strategies, including allosteric regulation, light-induced oligomerization, heterodimerization, and dissociation, and highlight representative applications targeting actin filaments, microtubules, and upstream signaling pathways such as Rho family GTPases. We conclude by outlining current limitations and emerging directions, including improved tissue penetration, reduced phototoxicity, and multiplexed optical control, which are expected to further expand the utility of optogenetics in cytoskeleton research.
14.
Enhancing the performance of Magnets photosensors.
Abstract:
Photosensory protein domains, derived from nature, are foundational for optogenetic protein engineering. Tailoring their properties enables their full exploitation for optogenetic regulation in basic research and applied bioengineering applications. Here, we present a simple, yet powerful strategy based on random mutagenesis coupled to high-throughput screening that allowed altering the most fundamental properties of the widely used nMag/pMag photodimerization system: its light sensitivity and activation. Variants were characterized in vivo in bacteria by flow cytometry and during the entire growth curve by spectrofluorometry. We identify mutations that either increase or decrease the light sensitivity at sub-saturating light intensities, while also improving the light activation and dark-to-light fold change. Notably, light sensitivity and activation levels could be changed independently. In addition, we demonstrated that the shapes of the dose-response curves can be finely tuned. This broadens the applicability of the Magnets photosensors for optogenetic regulation strategies.
15.
ShineGAL4 drivers for tissue and cell-type specific optogenetics in Drosophila.
Abstract:
An optogenetic split-GAL4 system, ShineGAL4, allows genes to be manipulated with unprecedented spatiotemporal precision. Here, we convert a panel of 14 GAL4 drivers widely used in Drosophila research into their ShineGAL4 counterparts. Homology assisted CRISPR knock-in (HACK) is used to replace GAL4 with the GAL4 DNA binding domain fused to a Magnet photoswitch. We show that the resulting ShineGAL4 drivers enable gene expression to be rapidly induced by light specifically in fat body, muscles, enterocytes, oenocytes, Malpighian tubules, neurons, neuroblast lineages, glial subtypes or in all glia. We also develop an optogenetic cassette for photoactivation of GAL4 in 'silent' FLP-out clones. This panel of optogenetic tools will enable precise spatiotemporal control of gene expression in a wide range of different Drosophila tissues and cell-types.
16.
Single-cell characterization of bacterial optogenetic Cre recombinases.
Abstract:
Microbial optogenetic tools can regulate gene expression with spatial and temporal precision, offering excellent potential for single-cell resolution studies. However, bacterial optogenetic systems have primarily been deployed for population-level experiments. It is not always clear how these tools perform in single cells, where stochastic effects can be substantial. In this study, we focus on optogenetic Cre recombinase and compare the performance of three variants (OptoCre-REDMAP, OptoCre-Vvd, and PA-Cre) for their population-level and single-cell activity. We quantify recombination efficiency, expression variability, and activation dynamics using reporters which produce changes in fluorescence or antibiotic resistance following light-induced Cre activity. We find that optogenetic recombinase performance can be reporter-dependent. Further, single-cell analysis reveals highly heterogeneous activity, with substantial variation in the efficiency and timing of recombinase activity from cell to cell. These findings suggest important criteria for selecting optogenetic recombinases and indicate areas for optimization to improve single-cell capabilities of bacterial optogenetic tools.
17.
Engineering microbial consortia for biosynthesis: Construction, regulation, and applications.
Abstract:
Synthetic microbial consortia (SMCs) represent a paradigm shift from monocultures to multi-strain systems that leverage ecological interactions for enhanced environmental adaptation and bioproduction. This review systematically sorts out engineering strategies for constructing stable SMCs, focusing on three core principles regarding host selection based on obligate mutualism (e.g., auxotrophs), pathway modularization to resolve metabolic conflicts, and dynamic regulation using tools like quorum sensing and optogenetics. We demonstrate the efficacy of SMCs in diverse applications including high-value compound synthesis and lignocellulosic biomass conversion through consolidated bioprocessing and inhibitor mitigation. SMCs enabling advanced functions in engineered living materials, environmental remediation, and biomedical innovation via division of labor are also described. Despite such progress, challenges in scalability and real-time control of SMCs under industrial conditions remain. We conclude that SMCs serve to bridge evolutionary ecology and biotechnology, offering robust solutions for sustainable biomanufacturing and beyond.
18.
Versatile applications of Light-Oxygen-Voltage (LOV) domain proteins in optical microscopy.
Abstract:
Various blue-light photoreceptor proteins have photo-responsive domains known as light, oxygen, voltage (LOV) domains, which are extensively distributed in plants, algae, fungi, and bacteria. When exposed to blue light, the flavin chromophore and a highly conserved cysteine residue form a covalent adduct on a microsecond time scale. LOV domains are common photosensory modules that can be applied to optogenetics, regulated synthesis of reactive oxygen species, and fluorescence microscopy. This review explores the photocycle kinetics and applications of various LOV domains, which have been explored for confocal microscopy, two-photon microscopy, and super-resolution microscopy. Many LOV domains have been derived and modulated for use in different types of microscopic applications. Molecular understanding, diversity of LOV domains, and versatile photo-physical characteristics of these proteins have immense potential for the development of useful probes for various microscopy tools. There is a great demand for perspective research on LOV domain proteins for harnessing their possible optobiotechnological applications.
19.
Single-cell analysis and control of microbial systems using optogenetics.
Abstract:
Single-cell resolution studies have transformed our understanding of microbial systems, revealing substantial cell-to-cell heterogeneity and complex dynamic behaviors. This review describes recent advances in using optogenetics, where light-sensitive proteins control cellular processes, to investigate microbial behavior at the individual cell level. We discuss studies where optogenetic approaches have enabled high-resolution analysis of properties such as relative cell positioning, subcellular localization, morphology, and gene expression dynamics. In addition, we highlight emerging feedback and event-driven control methods that dynamically modulate cellular states using light signals. By leveraging light's unique capabilities for spatial and temporal manipulation, researchers can now probe cellular characteristics with unprecedented precision. We anticipate significant advances as researchers introduce more sophisticated dynamically patterned light signals for single-cell microbial research.
20.
The cell biologist's guide to detecting and modulating membrane phospholipids.
Abstract:
Molecular biology has benefited enormously from repurposed tools-many enzymes and antibodies evolved for other functions but are now essential for interrogating biological function by manipulating proteins or nucleic acids. In contrast, lipids have remained technically difficult to visualize or manipulate in cells. This review introduces tools that bring lipid biology into reach for molecular cell biologists, using familiar experimental approaches. We first describe adaptations of immunofluorescence and live-cell imaging of fluorescent molecules to track lipids. Then, we discuss tools for manipulating lipid levels, including pharmacologic inhibitors, synthetic biology platforms for inducible lipid generation or degradation, and optogenetic systems for precise temporal control. While some methods remain technically demanding, most tools are now broadly accessible. Our goal is to offer a practical framework for integrating lipid biology into mainstream cell biology experiments.
21.
Design principles for optogenetic-based targeted protein degradation.
Abstract:
Precise regulation of protein abundance is essential for understanding dynamic cellular processes and for advancing therapeutic development. However, existing approaches lack the spatiotemporal resolution required to these cellular processes. Recent advances in optogenetics have enabled the design of optogenetic targeted protein degradation systems (Opto-TPD) allowing reversible and non-invasive control of protein stability with high spatiotemporal precision. In this review, we systematically summarize the design principles of Opto-TPD tools, including those based on light-oxygen-voltage (LOV)-domain conformational systems, light-inducible dimerization systems, and light-controlled degradation tool expression systems. We further highlight their applications in probing protein function, modulating signaling pathways, and therapeutic translations. By comparing the mechanistic features, performance, and limitations of each platform, we aim to provide a comprehensive resource for guiding future tool optimization. Altogether, these Opto-TPD tools represent a powerful and versatile complement to existing protein manipulation technologies, expanding the toolbox for precise control of protein homeostasis in living systems.
22.
Evolution and design shape protein dynamics in LOV domains - spanning picoseconds to days.
Abstract:
Light-sensitive proteins allow organisms to perceive and respond to their environment, and have diversified over billions of years. Among these, Light-Oxygen-Voltage (LOV) domains are widespread photosensors that control diverse physiological processes and are increasingly used in optogenetics. Yet, the evolutionary constraints that shaped their protein dynamics and thereby their functional diversity remain poorly resolved. Here we systematically characterize the dynamics of 21 natural LOV core domains, significantly extending the spectroscopically resolved catalog through the addition of 18 previously unstudied variants. Using time-resolved spectroscopy, we uncover an exceptional kinetic diversity spanning from picoseconds to days and identify distinct functional clusters within the LOV family. These clusters reflect evolutionary branching, including a divergence of ≈1.0 billion years between investigatedLOV variants from plants and ≈0.4 billion years of separation within one of these functional clusters. Individual variants with extreme photocycles emerge as promising anchor points for optogenetic applications, ranging from highly efficient adduct formation to ultrafast recovery. Beyond natural diversity, we introduce a LOV domain generated by artificial intelligence-guided protein design. Despite being sequentially remote from its maternal template, this variant retains core photocycle function while exhibiting unique biophysical properties, thereby occupying a new region on the biophysical landscape. Our work emphasizes how billions of years of evolution defined LOV protein dynamics, and how protein design can expand this repertoire, engineering next-generation optogenetic tools.
23.
Technological advances in visualizing and rewiring microtubules during plant development.
Abstract:
Microtubules are crucial regulators of plant development and are organized by a suite of microtubule-associated proteins (MAPs) that can rapidly remodel the array in response to various cues. This complexity has inspired countless studies into microtubule function from the subcellular to tissue scale, revealing an ever-increasing number of microtubule-dependent processes. Developing a comprehensive understanding of how local microtubule configuration, dynamicity, and remodeling drive developmental progression requires new approaches to capture and alter microtubule behavior. In this review, we will introduce the technological advancements we believe are poised to transform the study of microtubules in plant cells. In particular, we focus on (1) advanced imaging and analysis methods to quantify microtubule organization and behavior, and (2) novel tools to target specific microtubule populations in vivo. By showcasing innovative methodologies developed in non-plant systems, we hope to motivate their increased adoption and raise awareness of possible means of adapting them for studying microtubules in plants.
24.
Coiled-coil register transitions and coupling with the effector's inhibitory site enables high fold changes in blue light-regulated diguanylate cyclases.
Abstract:
Cellular signaling cascades rely on transfer of information from one protein to another or within a single protein. To facilitate signal integration, specific structural motifs evolved that allow signal processing and also enable modular downstream response integration, facilitating sophisticated regulatory mechanisms. On a structural level, especially coiled-coil helices are frequently observed as signaling motifs. In diguanylate cyclases (DGCs) featuring GGDEF domains, N-terminal coiled-coils frequently activate systems by rearrangements of the interdimer active site. The variety of sensory domains that modulate this structural equilibrium in response to different stimuli highlights the importance of DGCs in bacterial adaptation. One interesting example of sensor DGCs is blue light-activated light-oxygen-voltage (LOV)-GGDEF couples. Here, we describe molecular details of a two-stage mechanism that allows tight dark-state inhibition while enabling high enzymatic activities upon illumination, achieving fold changes exceeding 10,000-fold. Using an in vivo activity assay, we screened amino acid substitutions at the inhibitory interface and the sensor-effector linker region to identify variants that promote enzymatic activity in the dark. In combination with chimeras of LOV and GGDEF domains preventing inhibitory interface formation, we successfully stabilized elongated active-state conformations and confirmed the role of the inhibitory interface between sensor and effector in the tight dark-state inhibition. Interestingly, the initially generated chimeras are still light regulatable as long as the linker sequence is not stabilized in either inhibiting or stimulating coiled-coil register. Our results offer valuable insights for potential optogenetic applications but also demonstrate inherent challenges associated with Methylotenera sp. LOV-activated DGCs.
25.
Optogenetic control of biomolecular organization reveals distinct roles of phase separation in RTK signaling.
Abstract:
Multimerization and phase separation represent two paradigms for organizing receptor tyrosine kinases (RTKs). However, their functional distinctions from the perspective of biomolecular organization remain unclear. Here, we present CORdensate, a light-controllable condensation system combining two synergistic photoactuators: oligomeric Cry2 and heterodimeric LOVpep/ePDZ. Engineering single-chain photoswitches, we achieve four biomolecular organization patterns ranging from monomerization to phase separation. CORdensate exhibits constant assembly and disassembly kinetics. Applying CORdensate to mimic pathogenic RTK granules establishes the role of phase separation in activating ALK and RET. Moreover, assembling ALK and RET through varying organization patterns, we highlight the superior organizational ability of phase separation over multimerization. Additionally, CORdensate-based RTK granules suggest that phase separation broadly and robustly activates RTKs. This study introduces a optogenetic tool for investigating biomolecular condensation.