Curated Optogenetic Publication Database

Search precisely and efficiently by using the advantage of the hand-assigned publication tags that allow you to search for papers involving a specific trait, e.g. a particular optogenetic switch or a host organism.

Showing 26 - 50 of 113 results
26.

Light-based juxtacrine signaling between synthetic cells.

blue iLID in vitro Control of cell-cell / cell-material interactions
bioRxiv, 6 Jan 2024 DOI: 10.1101/2024.01.05.574425 Link to full text
Abstract: Cell signaling through direct physical cell-cell contacts plays vital roles in biology during development, angiogenesis, and immune response. Intercellular communication mechanisms between synthetic cells constructed from the bottom up are majorly reliant on diffusible chemical signals, thus limiting the range of responses in receiver cells. Engineering contact-dependent signaling between synthetic cells promises to unlock more complicated signaling schemes with different types of responses. Here, we design and demonstrate a light-activated contact-dependent communication tool for synthetic cells. We utilize a split bioluminescent protein to limit signal generation exclusively to contact interfaces of synthetic cells, driving the recruitment of a photoswitchable protein in receiver cells, akin to juxtacrine signaling in living cells. Our modular design not only demonstrates contact-dependent communication between synthetic cells but also provides a platform for engineering orthogonal contact-dependent signaling mechanisms.
27.

Pathogen infection induces sickness behaviors by recruiting neuromodulatory systems linked to stress and satiety in C. elegans.

blue bPAC (BlaC) C. elegans in vivo Immediate control of second messengers
bioRxiv, 5 Jan 2024 DOI: 10.1101/2024.01.05.574345 Link to full text
Abstract: When animals are infected by a pathogen, peripheral sensors of infection signal to the brain to coordinate a set of adaptive behavioral changes known as sickness behaviors. While the pathways that signal from the periphery to the brain have been intensively studied in recent years, how central circuits are reconfigured to elicit sickness behaviors is not well understood. Here we find that neuromodulatory systems linked to stress and satiety are recruited upon infection to drive sickness behaviors in C. elegans. Upon chronic infection by the bacterium Pseudomonas aeruginosa PA14, C. elegans decrease their feeding behavior, then display reversible bouts of quiescence, and eventually die. The ALA neuron and its neuropeptides FLP-7, FLP-24, and NLP-8, which control stress-induced sleep in uninfected animals, promote the PA14-induced feeding reduction. However, the ALA neuropeptide FLP-13 instead acts to delay quiescence and death in infected animals. Cell-specific genetic perturbations show that the neurons that release FLP-13 to delay quiescence in infected animals are distinct from ALA. A brain-wide imaging screen reveals that infection-induced quiescence involves ASI and DAF-7/TGF-beta, which control satiety-induced quiescence in uninfected animals. Our results suggest that a common set of neuromodulators are recruited across different physiological states, acting from distinct neural sources and in distinct combinations to drive state-dependent behaviors.
28.

Microsecond Molecular Dynamics Simulations and Markov State Models of Mutation-Induced Allosteric Mechanisms for the Light-Oxygen-Voltage 2 Protein : Revealing Structural Basis of Signal Transmission Induced by Photoactivation of the Light Protein State.

blue LOV domains Background
bioRxiv, 23 Dec 2023 DOI: 10.1101/2023.12.22.573121 Link to full text
Abstract: Avena Sativa phototropin 1 Light-oxygen-voltage 2 domain (AsLOV2) is the model protein of Per-Arnt-Sim (PAS) superfamily, characterized by conformational changes in response to external environmental stimuli. This conformational change is initiated by the unfolding of the N-terminal helix in the dark state followed by the unfolding of the C-terminal helix. The light state is defined by the unfolded termini and the subsequent modifications in hydrogen bond patterns. In this photoreceptor, β-sheets have been identified as crucial components for mediating allosteric signal transmission between the two termini. In this study, we combined microsecond all-atm molecular dynamics simulations and Markov state modeling of conformational states to quantify molecular basis of mutation-induced allostery in the AsLOV2 protein. Through a combination of computational investigations, we determine that the Hβ and Iβ strands are the most critical structural elements involved in the allosteric mechanism. To elucidate the role of these β-sheets, we introduced 13 distinct mutations (F490L, N492A, L493A, F494L, H495L, L496F, Q497A, R500A, F509L, Q513A, L514A, D515V, and T517V) and conducted comprehensive simulation analysis. The results highlighted the role of two hydrogen bond Asn482-Leu453 and Gln479-Val520 in the observed distinct behaviors of L493A, L496F, Q497A, and D515V mutants. The comprehensive atomistic-level analysis of the conformational landscapes revealed the critical functional role of β-sheet segments in the transmission of the allosteric signal upon the photoactivation of the light state.
29.

Rab3 mediates cyclic AMP-dependent presynaptic plasticity and olfactory learning.

blue bPAC (BlaC) D. melanogaster in vivo Immediate control of second messengers
bioRxiv, 22 Dec 2023 DOI: 10.1101/2023.12.21.572589 Link to full text
Abstract: Presynaptic forms of plasticity occur throughout the nervous system and play an important role in learning and memory but the underlying molecular mechanisms are insufficiently understood. Here we show that the small GTPase Rab3 is a key mediator of cyclic AMP (cAMP)-induced presynaptic plasticity in Drosophila. Pharmacological and optogenetic cAMP production triggered concentration-dependent alterations of synaptic transmission, including potentiation and depression of evoked neurotransmitter release, as well as strongly facilitated spontaneous release. These changes correlated with a nanoscopic rearrangement of the active zone protein Unc13A and required Rab3. To link these results to animal behaviour, we turned to the established role of cAMP signalling in memory formation and demonstrate that Rab3 is necessary for olfactory learning. As Rab3 is dispensable for basal synaptic transmission, these findings highlight a molecular pathway specifically dedicated to tuning neuronal communication and adaptive behaviour.
30.

Dynamic Multiplexed Control and Modeling of Optogenetic Systems Using the High-Throughput Optogenetic Platform, Lustro.

blue CRY2/CIB1 EL222 Magnets S. cerevisiae Transgene expression
bioRxiv, 20 Dec 2023 DOI: 10.1101/2023.12.19.572411 Link to full text
Abstract: The ability to control cellular processes using optogenetics is inducer-limited, with most optogenetic systems responding to blue light. To address this limitation, we leverage an integrated framework combining Lustro, a powerful high-throughput optogenetics platform, and machine learning tools to enable multiplexed control over blue light-sensitive optogenetic systems. Specifically, we identify light induction conditions for sequential activation as well as preferential activation and switching between pairs of light-sensitive spit transcription factors in the budding yeast, Saccharomyces cerevisiae. We use the high-throughput data generated from Lustro to build a Bayesian optimization framework that incorporates data-driven learning, uncertainty quantification, and experimental design to enable the prediction of system behavior and the identification of optimal conditions for multiplexed control. This work lays the foundation for designing more advanced synthetic biological circuits incorporating optogenetics, where multiple circuit components can be controlled using designer light induction programs, with broad implications for biotechnology and bioengineering.
31.

Impact of the clinically approved BTK inhibitors on the conformation of full-length BTK and analysis of the development of BTK resistance mutations in chronic lymphocytic leukemia.

blue CRY2clust MDCK Signaling cascade control Immediate control of second messengers
bioRxiv, 18 Dec 2023 DOI: 10.7554/elife.86727.2 Link to full text
Abstract: Inhibition of Bruton's tyrosine kinase (BTK) has proven to be highly effective in the treatment of B-cell malignancies such as chronic lymphocytic leukemia (CLL), autoimmune disorders and multiple sclerosis. Since the approval of the first BTK inhibitor (BTKi), Ibrutinib, several other inhibitors including Acalabrutinib, Zanubrutinib, Tirabrutinib and Pirtobrutinib have been clinically approved. All are covalent active site inhibitors, with the exception of the reversible active site inhibitor Pirtobrutinib. The large number of available inhibitors for the BTK target creates challenges in choosing the most appropriate BTKi for treatment. Side-by-side comparisons in CLL have shown that different inhibitors may differ in their treatment efficacy. Moreover, the nature of the resistance mutations that arise in patients appears to depend on the specific BTKi administered. We have previously shown that Ibrutinib binding to the kinase active site causes unanticipated long-range effects on the global conformation of BTK (Joseph, R.E., et al., 2020, https://doi.org/10.7554/eLife.60470 ). Here we show that binding of each of the five approved BTKi to the kinase active site brings about distinct allosteric changes that alter the conformational equilibrium of full-length BTK. Additionally, we provide an explanation for the resistance mutation bias observed in CLL patients treated with different BTKi and characterize the mechanism of action of two common resistance mutations: BTK T474I and L528W.
32.

An Integrated Optogenetic and Bioelectronic Platform for Regulating Cardiomyocyte Function.

blue bPAC (BlaC) rat cardiomyocytes Immediate control of second messengers
bioRxiv, 15 Dec 2023 DOI: 10.1101/2023.12.15.571704 Link to full text
Abstract: We report an integrated optogenetic and bioelectronic platform for stable and long-term modulation and monitoring of cardiomyocyte function in vitro. Optogenetic inputs were achieved through expression of a photoactivatable adenylyl cyclase (bPAC), that when activated by blue light caused a dose-dependent and time-limited increase in autonomous cardiomyocyte beat rate. Bioelectronic readouts were achieved through an integrated planar multi-electrode array (MEA) that provided real-time readouts of electrophysiological activity from 32 spatially-distinct locations. Irradiation at 27 μW/mm2 resulted in a ca. 14% increase in beat rate within 20-25 minutes, which remained stable for at least 2 hours. The beating rate could be cycled through repeated “on” and “off” states, and its magnitude was a monotonic function of irradiation intensity. Our integrated platform opens new avenues in bioelectronic medicine, including closedloop feedback systems, with potential applications for cardiac regulation including arrhythmia diagnosis and intervention.
33.

Liebig’s law of the minimum in the TGF-β/SMAD pathway.

blue CRY2/CIB1 HeLa Signaling cascade control
bioRxiv, 6 Dec 2023 DOI: 10.1101/2023.07.10.548398 Link to full text
Abstract: Cells use signaling pathways to sense and respond to their environments. The transforming growth factor-β (TGF-β) pathway produces context-specific responses. Here, we combined modeling and experimental analysis to study the dependence of the output of the TGF-β pathway on the abundance of signaling molecules in the pathway. We showed that the TGF-β pathway processes the variation of TGF-β receptor abundance using Liebig’s law of the minimum, meaning that the output-modifying factor is the signaling protein that is most limited, to determine signaling responses across cell types and in single cells. We found that the abundance of either the type I (TGFBR1) or type II (TGFBR2) TGF-β receptor determined the responses of cancer cell lines, such that the receptor with relatively low abundance dictates the response. Furthermore, nuclear SMAD2 signaling correlated with the abundance of TGF_x0002_β receptor in single cells depending on the relative expression levels of TGFBR1 and TGFBR2. A similar control principle could govern the heterogeneity of signaling responses in other signaling pathways.
34.

Regulatable assembly of synthetic microtubule architectures using engineered MAP-IDR condensates.

blue CRY2/CRY2 PixD/PixE NIH/3T3 Control of cytoskeleton / cell motility / cell shape Organelle manipulation
bioRxiv, 6 Dec 2023 DOI: 10.1101/2023.03.14.532644 Link to full text
Abstract: Microtubules filaments are assembled into higher-order structures and machines critical for cellular processes using microtubule-associated proteins (MAPs). However, the design of synthetic MAPs that direct the formation of new structures in cells is challenging, as nanoscale biochemical activities must be organized across micron length-scales. Here we develop synthetic MAP-IDR condensates (synMAPs) that provide tunable and regulatable assembly of higher-order microtubule structures in vitro and in mammalian cells. synMAPs harness a small microtubule-binding domain from oligodendrocytes (TPPP) whose activity can be synthetically rewired by interaction with condensate-forming IDR sequences. This combination allows synMAPs to self-organize multivalent structures that bind and bridge microtubules into synthetic architectures. Regulating the connection between the microtubule-binding and condensate-forming components allows synMAPs to act as nodes in more complex cytoskeletal circuits in which the formation and dynamics of the microtubule structure can be controlled by small molecules or cell-signaling inputs. By systematically testing a panel of synMAP circuit designs, we define a two-level control scheme for dynamic assembly of microtubule architectures at the nanoscale (via microtubule-binding) and microscale (via condensate formation). synMAPs provide a compact and rationally engineerable starting point for the design of more complex microtubule architectures and cellular machines.
35.

A red light-induced genetic system for control of extracellular electron transfer.

blue red iLight YtvA E. coli Transgene expression Multichromatic
bioRxiv, 2 Dec 2023 DOI: 10.1101/2023.12.02.569691 Link to full text
Abstract: Optogenetics is a powerful tool for spatiotemporal control of gene expression. Several light-inducible gene regulators have been developed to function in bacteria, and these regulatory circuits have been ported into new host strains. Here, we developed and adapted a red light-inducible transcription factor for Shewanella oneidensis. This regulatory circuit is based on the iLight optogenetic system, which controls gene expression using red light. Promoter engineering and a thermodynamic model were used to adapt this system to achieve differential gene expression in light and dark conditions within a S. oneidensis host strain. We further improved the iLight optogenetic system by adding a repressor to invert the genetic circuit and activate gene expression under red light illumination. The inverted iLight genetic circuit was used to control extracellular electron transfer (EET) within S. oneidensis. The ability to use both red and blue light-induced optogenetic circuits simultaneously was demonstrated. Our work expands the synthetic biology toolbox of Shewanella, which could facilitate future advances in applications with electrogenic bacteria.
36.

Prior Fc Receptor activation primes macrophages for increased sensitivity to IgG via long term and short term mechanisms.

blue CRY2olig RAW264.7 Signaling cascade control Control of vesicular transport
bioRxiv, 14 Nov 2023 DOI: 10.1101/2023.11.14.567059 Link to full text
Abstract: Macrophages measure the ‘eat-me’ signal IgG to identify targets for phagocytosis. We wondered if prior encounters with IgG influence macrophage appetite. IgG is recognized by the Fc Receptor. To temporally control Fc Receptor activation, we engineered an Fc Receptor that is activated by light-induced oligomerization of Cry2, triggering phagocytosis. Using this tool, we demonstrate that Fc Receptor activation primes macrophages to be more sensitive to IgG in future encounters. Macrophages that have previously experienced Fc Receptor activation eat more IgG-bound cancer cells. Increased phagocytosis occurs by two discrete mechanisms – a short- and long-term priming. Long term priming requires new protein synthesis and Erk activity. Short term priming does not require new protein synthesis and correlates with an increase in Fc Receptor mobility. Our work demonstrates that IgG primes macrophages for increased phagocytosis, suggesting that therapeutic antibodies may become more effective after 30 initial priming doses.
37.

Light induced expression of gRNA allows for optogenetic gene editing of T lymphocytes in vivo.

blue EL222 HEK293FT HEK293T mouse in vivo mouse T cells Transgene expression Endogenous gene expression Nucleic acid editing
bioRxiv, 10 Nov 2023 DOI: 10.1101/2023.11.09.566272 Link to full text
Abstract: There is currently a lack of tools capable of perturbing genes in both a precise and spatiotemporal fashion. CRISPR’s ease of use and flexibility, coupled with light’s unparalleled spatiotemporal resolution deliverable from a controllable source, makes optogenetic CRISPR a well-suited solution for precise spatiotemporal gene perturbations. Here we present a new optogenetic CRISPR tool, BLU-VIPR, that diverges from prevailing split-Cas design strategies and instead focuses on optogenetic regulation of gRNA production. This simplifies spatiotemporal gene perturbation and works in vivo with cells previously intractable to optogenetic gene editing. We engineered BLU-VIPR around a new potent blue-light activated transcription factor and ribozyme-flanked gRNA. The BLU-VIPR design is genetically encoded and ensures precise excision of multiple gRNAs from a single mRNA transcript, allowing for optogenetic gene editing in T lymphocytes in vivo.
38.

Capturing the blue-light activated state of the Phot-LOV1 domain from Chlamydomonas reinhardtii using time-resolved serial synchrotron crystallography.

blue LOV domains Background
bioRxiv, 6 Nov 2023 DOI: 10.1101/2023.11.06.565770 Link to full text
Abstract: Light-Oxygen-Voltage (LOV) domains are small photosensory flavoprotein modules that allow converting external stimuli (sunlight) into intracellular signals responsible for various cell behavior (e.g., phototropism and chloroplast relocation). This ability relies on the light-induced formation of a covalent thioether adduct between a flavin chromophore and a reactive cysteine from the protein environment, which triggers a cascade of structural changes that results in the activation of a serine/threonine (Ser/Thr) kinase. Recent developments in time-resolved crystallography may allow the observation of the activation cascade of the LOV domain in real-time, which has been elusive. In this study, we report a robust protocol for the production and stable delivery of microcrystals of the LOV domain of phototropin Phot-1 from Chlamydomonas reinhardtii (CrPhotLOV1) with a high-viscosity injector for time-resolved serial synchrotron crystallography (TR-SSX). The detailed process covers all aspects, from sample optimization to the actual data collection process, which may serve as a guide for soluble protein preparation for TR-SSX. In addition, we show that the obtained crystals preserve the photoreactivity using infrared spectroscopy. Furthermore, the results of the TR-SSX experiment provide high-resolution insights into structural alterations of CrPhotLOV1 from Δt = 2.5 ms up to Δt = 95 ms post-photoactivation, including resolving the geometry of the thioether adduct and the C-terminal region implicated in the signal transduction process.
39.

Critical capillary waves of biomolecular condensates.

blue iLID U-2 OS Organelle manipulation
bioRxiv, 5 Nov 2023 DOI: 10.1101/2023.10.29.564316 Link to full text
Abstract: Membraneless compartments known as biomolecular condensates are thought to form through liquid-liquid phase separation (LLPS). When forces are applied to the fluid interfaces of these condensates, surface fluctuation are generated, a phenomenon known as capillary waves. The spatiotemporal dynamics of these fluctuations, characterized by the amplitude and velocity, reflect the physical properties of condensates. Moreover, unraveling the nature of fluctuations near the critical point is crucial for understanding the universal physical underpinnings of phase transitions. Although fluid condensate interfaces are ubiquitous within living cells, little is known about their surface fluctuations. Here, we quantify the interface fluctuations of light-induced synthetic and endogenous nuclear condensates, including nucleoli and nuclear speckles, in real and Fourier space. Measured fluctuations align with a theory assuming thermal driving, which enables measurement of surface tension and effective viscosity. The surface tensions fall within the range of 10−6 to 10−5 N/m for all tested condensates; in contrast, we find significant difference of fluctuation velocities, highlighting much higher viscosity of nucleoli ∼ 104 Pa·s, compared to synthetic condensates and nuclear speckles. We further find that the interface fluctuations become enhanced and slower as the system nears the critical point. These findings elucidate key aspects of intracellular condensate properties, and suggest that the critical trend of surface tension is more consistent with theoretical predictions by the mean-field model than those by the 3D Ising model.
40.

RudLOV—a new optically synchronized cargo transport method reveals unexpected effect of dynasore.

blue LOVTRAP HeLa Control of vesicular transport
bioRxiv, 5 Nov 2023 DOI: 10.1101/2023.11.04.565648 Link to full text
Abstract: Live imaging of secretory cargoes is a powerful method for understanding the mechanisms of membrane trafficking. Inducing the synchronous release of cargoes from an organelle is a key for enhancing microscopic observation. We developed an optical cargo-releasing method named as retention using dark state of LOV2 (RudLOV), which enables exceptional spatial, temporal, and quantity control during cargo release. A limited amount of cargo-release using RudLOV successfully visualized cargo cisternal-movement and cargo-specific exit sites on the Golgi/trans-Golgi network. Moreover, by controlling the timing of cargo-release using RudLOV, we revealed the canonical and non-canonical effects of the well-known dynamin inhibitor dynasore, which inhibits early-Golgi but not late-Golgi transport and exit from the trans-Golgi network where dynamin-2 is active. Accumulation of COPI vesicles at the cis-side of the Golgi stacks in dynasore-treated cells suggests that dynasore targets COPI-uncoating/tethering/fusion machinery in the early-Golgi cisternae or endoplasmic reticulum but not in the late-Golgi cisternae. These results provide insight into the cisternal maturation of Golgi stacks.
41.

Turn-On Protein Switches for Controlling Actin Binding in Cells.

blue AsLOV2 HEK293T HeLa MDCK Control of cytoskeleton / cell motility / cell shape
bioRxiv, 26 Oct 2023 DOI: 10.1101/2023.10.26.561921 Link to full text
Abstract: Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP’s influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into new structures to control cell and tissue shape and behavior.
42.

Light-driven synchronization of optogenetic clocks.

green CcaS/CcaR E. coli Cell cycle control Transgene expression
bioRxiv, 24 Oct 2023 DOI: 10.1101/2023.10.24.563722 Link to full text
Abstract: Synthetic genetic oscillators can serve as internal clocks within engineered cells to program periodic expression. However, cell-to-cell variability introduces a dispersion in the characteristics of these clocks that drives the population to complete desynchronization. Here we introduce the optorepressilator, an optically controllable genetic clock that combines the repressilator, a three-node synthetic network in E. coli, with an optogenetic module enabling to reset, delay, or advance its phase using optical inputs. We demonstrate that a population of optorepressilators can be synchronized by transient green light exposure or entrained to oscillate indefinitely by a train of short pulses, through a mechanism reminiscent of natural circadian clocks. Furthermore, we investigate the system’s response to detuned external stimuli observing multiple regimes of global synchronization. Integrating experiments and mathematical modeling, we show that the entrainment mechanism is robust and can be understood quantitatively from single cell to population level.
43.

Light-induced trapping of endogenous proteins reveals spatiotemporal roles of microtubule and kinesin-1 in dendrite patterning of Drosophila sensory neurons.

blue CRY2/CIB1 CRY2/CRY2 CRY2olig Magnets D. melanogaster in vivo Control of cytoskeleton / cell motility / cell shape
bioRxiv, 2 Oct 2023 DOI: 10.1101/2023.09.30.560303 Link to full text
Abstract: Animal development involves numerous molecular events, whose spatiotemporal properties largely determine the biological outcomes. Conventional methods for studying gene function lack the necessary spatiotemporal resolution for precise dissection of developmental mechanisms. Optogenetic approaches are powerful alternatives, but most existing tools rely on exogenous designer proteins that produce narrow outputs and cannot be applied to diverse or endogenous proteins. To address this limitation, we developed OptoTrap, a light-inducible protein trapping system that allows manipulation of endogenous proteins tagged with GFP or split GFP. This system turns on fast and is reversible in minutes or hours. We generated OptoTrap variants optimized for neurons and epithelial cells and demonstrate effective trapping of endogenous proteins of diverse sizes, subcellular locations, and functions. Furthermore, OptoTrap allowed us to instantly disrupt microtubules and inhibit the kinesin-1 motor in specific dendritic branches of Drosophila sensory neurons. Using OptoTrap, we obtained direct evidence that microtubules support the growth of highly dynamic dendrites. Similarly, targeted manipulation of Kinesin heavy chain revealed differential spatiotemporal requirements of kinesin-1 in the patterning of low- and high-order dendritic branches, suggesting that different cargos are needed for the growth of these branches. OptoTrap allows for precise manipulation of endogenous proteins in a spatiotemporal manner and thus holds great promise for studying developmental mechanisms in a wide range of cell types and developmental stages.
44.

Allosteric regulation of kinase activity in living cells.

blue cyan red Fluorescent proteins LOV domains Phytochromes Review
bioRxiv, 25 Sep 2023 DOI: 10.1101/2023.07.19.549709 Link to full text
Abstract: The dysregulation of protein kinases is associated with multiple diseases due to the kinases’ involvement in a variety of cell signaling pathways. Manipulating protein kinase function, by controlling the active site, is a promising therapeutic and investigative strategy to mitigate and study diseases. Kinase active sites share structural similarities making it difficult to specifically target one kinase, allosteric control allows specific regulation and study of kinase function without directly targeting the active site. Allosteric sites are distal to the active site but coupled via a dynamic network of inter-atomic interactions between residues in the protein. Establishing an allosteric control over a kinase requires understanding the allosteric wiring of the protein. Computational techniques offer effective and inexpensive mapping of the allosteric sites on a protein. Here, we discuss methods to map and regulate allosteric communications in proteins, and strategies to establish control over kinase functions in live cells and organisms. Protein molecules, or “sensors” are engineered to function as tools to control allosteric activity of the protein as these sensors have high spatiotemporal resolution and help in understanding cell phenotypes after immediate activation or inactivation of a kinase. Traditional methods used to study protein functions, such as knockout, knockdown, or mutation, cannot offer a sufficiently high spatiotemporal resolution. We discuss the modern repertoire of tools to regulate protein kinases as we enter a new era in deciphering cellular signaling and developing novel approaches to treat diseases associated with signal dysregulation.
45.

Tuning of B12 photochemistry in the CarH photoreceptor to avoid radical photoproduct

green Cobalamin-binding domains Background
bioRxiv, 21 Sep 2023 DOI: 10.1101/2023.08.11.552799 Link to full text
Abstract: Time-resolved infrared spectroscopy reveals the flow of electron density through coenzyme B12 in the lightactivated, bacterial transcriptional regulator, CarH. The protein stabilises a series of charge transfer states that result in a photoresponse that avoids reactive, and potentially damaging, radical photoproducts.
46.

Photoswitchable binders enable temporal dissection of endogenous protein function.

cyan pdDronpa1 HeLa U-87 MG Signaling cascade control Control of cytoskeleton / cell motility / cell shape
bioRxiv, 14 Sep 2023 DOI: 10.1101/2023.09.14.557687 Link to full text
Abstract: General methods for spatiotemporal control of specific endogenous proteins would be broadly useful for probing protein function in living cells. Synthetic protein binders that bind and inhibit endogenous protein targets can be obtained from nanobodies, designed ankyrin repeat proteins (DARPins), and other small protein scaffolds, but generalizable methods to control their binding activity are lacking. Here, we report robust single-chain photoswitchable DARPins (psDARPins) for bidirectional optical control of endogenous proteins. We created topological variants of the DARPin scaffold by computer-aided design so fusion of photodissociable dimeric Dronpa (pdDronpa) results in occlusion of target binding at baseline. Cyan light induces pdDronpa dissociation to expose the binding surface (paratope), while violet light restores pdDronpa dimerization and paratope caging. Since the DARPin redesign leaves the paratope intact, the approach was easily applied to existing DARPins for GFP, ERK, and Ras, as demonstrated by relocalizing GFP-family proteins and inhibiting endogenous ERK and Ras with optical control. Finally, a Ras-targeted psDARPin was used to determine that, following EGF-activation of EGFR, Ras is required for sustained EGFR to ERK signaling. In summary, psDARPins provide a generalizable strategy for precise spatiotemporal dissection of endogenous protein function.
47.

Control of cell retraction and protrusion with a single protein.

blue iLID hTERT RPE-1 Control of cytoskeleton / cell motility / cell shape
bioRxiv, 8 Sep 2023 DOI: 10.1101/2023.09.07.556666 Link to full text
Abstract: The ability of a single protein to trigger different functions is an assumed key feature of cell signaling, yet there are very few examples demonstrating it. Here, using an optogenetic tool to control membrane localization of RhoA nucleotide exchange factors (GEFs), we present a case where the same protein can trigger both protrusion and retraction when recruited to the plasma membrane, polarizing the cell in two opposite directions. We show that the basal concentration of the GEF prior to activation predicts the resulting phenotype. A low concentration leads to retraction, whereas a high concentration triggers protrusion. This unexpected protruding behavior arises from the simultaneous activation of Cdc42 by the GEF and inhibition of RhoA by the PH domain of the GEF at high concentrations. We propose a minimal model that recapitulates the phenotypic switch, and we use its predictions to control the two phenotypes within selected cells by adjusting the frequency of light pulses. Our work exemplifies a unique case of control of antagonist phenotypes by a single protein that switches its function based on its concentration or dynamics of activity. It raises numerous open questions about the link between signaling protein and function, particularly in contexts where proteins are highly overexpressed, as often observed in cancer.
48.

Opto4E-BP, an optogenetic tool for inducible, reversible, and cell type-specific inhibition of translation initiation.

blue cpLOV2 HEK293 mouse in vivo primary mouse cortical neurons Transgene expression
bioRxiv, 31 Aug 2023 DOI: 10.1101/2023.08.30.554643 Link to full text
Abstract: The protein kinase mechanistic target of rapamycin complex 1 (mTORC1) is one of the primary triggers for initiating cap-dependent translation. Amongst its functions, mTORC1 phosphorylates eIF4E-binding proteins (4E-BPs), which prevents them from binding to eIF4E and thereby enables translation initiation. mTORC1 signaling is required for multiple forms of protein synthesis- dependent synaptic plasticity and various forms of long-term memory (LTM), including associative threat memory. However, the approaches used thus far to target mTORC1 and its effectors, such as pharmacological inhibitors or genetic knockouts, lack fine spatial and temporal control. The development of a conditional and inducible eIF4E knockdown mouse line partially solved the issue of spatial control, but still lacked optimal temporal control to study memory consolidation. Here, we have designed a novel optogenetic tool (Opto4E-BP) for cell type-specific, light-dependent regulation of eIF4E in the brain. We show that light-activation of Opto4E-BP decreases protein synthesis in HEK cells and primary mouse neurons. In situ, light-activation of Opto4E-BP in excitatory neurons decreased protein synthesis in acute amygdala slices. Finally, light activation of Opto4E-BP in principal excitatory neurons in the lateral amygdala (LA) of mice after training blocked the consolidation of LTM. The development of this novel optogenetic tool to modulate eIF4E-dependent translation with spatiotemporal precision will permit future studies to unravel the complex relationship between protein synthesis and the consolidation of LTM.
49.

OptoPI3K, genetic code expansion, and click chemistry reveal mechanisms underlying reciprocal regulation between TRPV1 and PI3K.

red PhyB/PIF F-11 HEK293T/17 NIH/3T3 Signaling cascade control
bioRxiv, 30 Aug 2023 DOI: 10.1101/2023.08.29.555449 Link to full text
Abstract: Receptor tyrosine kinase signaling is characterized by complex webs of interconnected pathways that regulate diverse cellular functions. The complexity of signaling is a barrier to understanding the pathways that control any particular function. In this work, we use a novel combination of approaches and a new click chemistry probe to determine the role of one pathway in regulating cell surface expression of an ion channel and a receptor tyrosine kinase. We applied an optogenetic approach to uncouple activation of the PI3K pathway from other pathways downstream of RTK activation. In this context, we used genetic code expansion to introduce a click chemistry noncanonical amino acid into the extracellular side of membrane proteins. Applying a cell-impermeant click chemistry fluorophore allowed us to visualize delivery of membrane proteins to the PM in real time. Using these approaches, we demonstrate that activation of PI3K, without activating other pathways downstream of RTK signaling, is sufficient to traffic the TRPV1 ion channels and insulin receptors to the plasma membrane.
50.

An optogenetic approach to control and monitor inflammasome activation.

blue CRY2/CRY2 iBMDM MEF-1 Cell death
bioRxiv, 28 Aug 2023 DOI: 10.1101/2023.07.25.550490 Link to full text
Abstract: Inflammasomes are multiprotein platforms which control caspase-1 activation, leading to the processing of proinflammatory cytokines into mature and active cytokines IL-1β and IL-18, and to pyroptosis through the cleavage of gasdermin-D (GSDMD). Inflammasomes assemble upon activation of specific cytosolic pattern recognition receptors (PRRs) by damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). They converge to the nucleation of apoptosis-associated speck-like containing a caspase activation and recruitment domain (ASC) to form hetero-oligomers with caspase-1. Studying inflammasome encoding activities remains challenging because PAMPs and DAMPs are sensed by a large diversity of cytosolic and membranous PRRs. To bypass the different signals required to activate the inflammasome, we designed an optogenetic approach to temporally and quantitatively manipulate ASC assembly (i.e. in a PAMP- or DAMP-independent manner). We reveal that controlling light-sensitive oligomerization of ASC is sufficient to recapitulate the classical features of inflammasomes within minutes, and enabled us to decipher the complexity of volume regulation and pore opening during pyroptosis. Overall, this approach offers interesting perspective to decipher PRR signaling pathways in the field of innate immunity.
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