Source 1primary paper2024
Toolkit/Avena sativa phototropin-1 LOV2 domain
Avena sativa phototropin-1 LOV2 domain
Also known as: As LOV2, LOV2 domain, LOV2 domain from Avena sativa phototropin 1
Taxonomy: Mechanism Branch / Component. Workflows sit above the mechanism and technique branches rather than replacing them.
Summary
The Avena sativa phototropin-1 LOV2 domain is a blue-light-sensing flavin-binding photosensory domain used as a module for light-controlled conformational uncaging. Available evidence shows that its dark-state recovery follows a base-catalyzed mechanism and that its light responsiveness is influenced by the flavin redox state.
Usefulness & Problems
Why this is useful
As LOV2 is useful as a genetically encoded photosensory module for coupling blue light input to conformational changes in engineered proteins. The supplied evidence further indicates that its redox properties can tune photosensitivity, which is relevant when deploying the domain in intracellular environments.
Problem solved
This domain helps solve the problem of achieving optical control over protein conformation and downstream signaling with a compact flavin-binding sensor. The cited studies also address the problem of understanding how dark-state recovery kinetics and intracellular redox conditions affect LOV2-based tool performance.
Problem links
Need conditional control of signaling activity
DerivedThe Avena sativa phototropin-1 LOV2 domain is a blue-light-sensing flavin-binding protein domain used as a photosensory module for light-controlled conformational uncaging. Available evidence indicates that its dark-state recovery proceeds through a base-catalyzed mechanism and that its redox state can modulate light responsiveness.
Need conditional recombination or state switching
DerivedThe Avena sativa phototropin-1 LOV2 domain is a blue-light-sensing flavin-binding protein domain used as a photosensory module for light-controlled conformational uncaging. Available evidence indicates that its dark-state recovery proceeds through a base-catalyzed mechanism and that its redox state can modulate light responsiveness.
Need precise spatiotemporal control with light input
DerivedThe Avena sativa phototropin-1 LOV2 domain is a blue-light-sensing flavin-binding protein domain used as a photosensory module for light-controlled conformational uncaging. Available evidence indicates that its dark-state recovery proceeds through a base-catalyzed mechanism and that its redox state can modulate light responsiveness.
Taxonomy & Function
Primary hierarchy
Mechanism Branch
Component: A low-level protein part used inside a larger architecture that realizes a mechanism.
Mechanisms
base-catalyzed dark-state recoverybase-catalyzed dark-state recoveryconformational uncagingconformational uncagingConformational UncagingTechniques
No technique tags yet.
Target processes
recombinationsignalingInput: Light
Implementation Constraints
cofactor dependency: cofactor requirement unknownencoding mode: genetically encodedimplementation constraint: context specific validationimplementation constraint: spectral hardware requirementoperating role: sensorswitch architecture: uncaging
As LOV2 is a flavin-binding domain and therefore depends on a flavin cofactor for photosensing. The available evidence indicates that intracellular redox conditions may partially reduce the domain at its approximately -280 mV midpoint potential, and site-directed methionine substitutions near the flavin alter both reduction potential and photoactivation behavior.
Methionine introduction near the flavin impairs photoactivation efficiency and reduces light sensitivity, indicating a tradeoff between redox tuning and optical performance. The evidence provided does not include quantitative validation in specific fusion constructs, cellular assays, or organismal applications beyond mechanistic and biophysical characterization.
Validation
Cell-freeBacteriaMammalianMouseHumanTherapeuticIndep. Replication
Supporting Sources
Source 2primary paper2007Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology
Ranked Claims
Although individual methionine substitutions affect signaling-state stability and downstream allosteric responses, no clear-cut correlation with redox properties emerges.
Although individual methionine substitutions also affect the stability of the signaling state and downstream allosteric responses, no clear-cut correlation with the redox properties emerges.
Methionine substitutions near the flavin consistently increase the reduction midpoint potential of As LOV2 by up to 40 mV.
Replacements of residues at different sites near the flavin by methionine consistently increase E 0 from its value of around 280 mV by up to 40 mV.
reduction midpoint potential increase 40 mV
Methionine introduction impairs photoactivation efficiency and makes As LOV2 variants less light-sensitive.
Moreover, methionine introduction invariably impairs photoactivation efficiency and thus renders the resultant As LOV2 variants less light-sensitive.
Because As LOV2 has a reduction midpoint potential near -280 mV, it may be partially reduced inside cells, which directly affects light responsiveness.
With a reduction midpoint potential near 280 mV, As LOV2 and, by inference, other LOV receptors may be partially reduced inside cells which directly affects their light responsiveness.
reduction midpoint potential -280 mV
The reduction midpoint potential of As LOV2 is around -280 mV.
Replacements of residues at different sites near the flavin by methionine consistently increase E 0 from its value of around 280 mV
reduction midpoint potential -280 mV
Dark state recovery in the Avena sativa phototropin-1 LOV2 domain proceeds by a base-catalyzed mechanism.
A base-catalyzed mechanism for dark state recovery in the Avena sativa phototropin-1 LOV2 domain
Approval Evidence
6 sources25 linked approval claimsfirst-pass slug avena-sativa-phototropin-1-lov2-domain
we here investigate the reduction midpoint potential E 0 in the paradigm LOV2 domain from Avena sativa phototropin 1 ( As LOV2)
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The Light-Oxygen-Voltage 2 (LOV2) domain of Avena Sativa phototropin 1 (AsLOV2) protein is one of the most studied domains in the field of designing photoswitches.
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The primary reactions of the Avena sativa phototropin 1 LOV2 domain were investigated
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Q513 in the Avena sativa phototropin 1 LOV2 (AsLOV2) domain
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A base-catalyzed mechanism for dark state recovery in the Avena sativa phototropin-1 LOV2 domain
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We report that the imidazole base can act as a very efficient enhancer of the dark recovery of A. sativa phot1 LOV2 (AsLOV2)
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correlation assessmentsupports
Although individual methionine substitutions affect signaling-state stability and downstream allosteric responses, no clear-cut correlation with redox properties emerges.
Although individual methionine substitutions also affect the stability of the signaling state and downstream allosteric responses, no clear-cut correlation with the redox properties emerges.
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engineering effectsupports
Methionine substitutions near the flavin consistently increase the reduction midpoint potential of As LOV2 by up to 40 mV.
Replacements of residues at different sites near the flavin by methionine consistently increase E 0 from its value of around 280 mV by up to 40 mV.
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engineering tradeoffsupports
Methionine introduction impairs photoactivation efficiency and makes As LOV2 variants less light-sensitive.
Moreover, methionine introduction invariably impairs photoactivation efficiency and thus renders the resultant As LOV2 variants less light-sensitive.
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physiological implicationsupports
Because As LOV2 has a reduction midpoint potential near -280 mV, it may be partially reduced inside cells, which directly affects light responsiveness.
With a reduction midpoint potential near 280 mV, As LOV2 and, by inference, other LOV receptors may be partially reduced inside cells which directly affects their light responsiveness.
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redox propertysupports
The reduction midpoint potential of As LOV2 is around -280 mV.
Replacements of residues at different sites near the flavin by methionine consistently increase E 0 from its value of around 280 mV
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mechanistic rolesupports
Beta sheets have a significant role in the overall allosteric process of AsLOV2.
Moreover, the community analysis highlighted the significant role of the β sheets in the overall protein allosteric process.
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mechanistic rolesupports
Maintaining the N-terminal hydrogen bond network is essential for the transition between the light and dark states of AsLOV2.
Maintaining the N-terminal hydrogen bond network was found to be essential for the transition between the two states.
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residue functionsupports
Thr407 and Arg410 are key residues involved in the functional conformational switch and affect overall AsLOV2 protein dynamics.
Via in-depth hydrogen bonding and contact analysis we were able to identify key residues (Thr407 and Arg410) involved in the functional conformational switch and their impact on the overall protein dynamics.
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structural propertysupports
AsLOV2 has a monomeric structure in both light and dark states and a relatively short transition time between the two states.
This is due to the several unique features in the AsLOV2, such as the monomeric structure of the protein in both light and dark states and the relatively short transition time between the two states.
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tool relevancesupports
The Avena sativa phototropin 1 LOV2 domain is one of the most studied domains for designing photoswitches.
The Light-Oxygen-Voltage 2 (LOV2) domain of Avena Sativa phototropin 1 (AsLOV2) protein is one of the most studied domains in the field of designing photoswitches.
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assignmentsupports
A weak long-lived emission component from 600 to 650 nm in LOV2 was assigned to phosphorescence from the reactive FMN triplet state.
A weak long-lived component with emission intensity from 600 to 650 nm was assigned to phosphorescence from the reactive FMN triplet state.
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measurementsupports
The Avena sativa phototropin 1 LOV2 domain has a fluorescence lifetime of 2.2 ns.
Synchroscan streak camera experiments revealed a fluorescence lifetime of 2.2 ns in LOV2.
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measurementsupports
The fluorescence quantum yield of LOV2 increased from 0.13 to 0.41 when the sample was cooled from 293 K to 77 K.
The fluorescence quantum yield of LOV2 increased from 0.13 to 0.41 upon cooling the sample from 293 to 77 K.
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measurementsupports
The LOV2 triplet state energy level at physiological temperature was determined to be 16600 cm(-1).
This observation allowed determination of the LOV2 triplet state energy level at physiological temperature at 16600 cm(-1).
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mechanismsupports
Phototropin light-dependent action is based on reversible formation of a covalent bond between an FMN cofactor and a conserved cysteine in LOV domains.
The phototropins are blue-light receptors that base their light-dependent action on the reversible formation of a covalent bond between a flavin mononucleotide (FMN) cofactor and a conserved cysteine in light, oxygen or voltage (LOV) domains.
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observationsupports
A pronounced phosphorescence emission around 600 nm was observed in the LOV2 domain between 77 and 120 K in steady-state emission.
A pronounced phosphorescence emission around 600 nm was observed in the LOV2 domain between 77 and 120 K in the steady-state emission.
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mechanistic rolesupports
In AsLOV2, the conserved glutamine residue Q513 plays a central role in spectral tuning and in signal propagation from the LOV core through the Ibeta strand to the peripheral Jalpha helix.
Together, these data establish that this residue plays a central role in both spectral tuning and signal propagation from the core of the LOV domain through the Ibeta strand to the peripheral Jalpha helix.
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mutation effectsupports
Q513L and Q513N mutations in AsLOV2 significantly dampen the structural changes between dark and lit states, producing pseudodark and pseudolit states respectively.
The results show that these mutations significantly dampen the changes between the dark and lit state AsLOV2 structures, leaving the protein in a pseudodark state (Q513L) or a pseudolit state (Q513N).
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photochemical property changesupports
Q513L and Q513N mutations alter the photochemical properties of AsLOV2, including the lifetime of the photoexcited signaling states.
Further, both mutations changed the photochemical properties of this receptor, in particular the lifetime of the photoexcited signaling states.
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kinetic contributionsupports
Processes other than histidine-mediated base catalysis contribute substantially to adduct thermal decay in AsLOV2.
In addition, molecular processes other than histidine-mediated base catalysis contibute significantly to the total thermal decay rate of the adduct and operate at a rate constant of (65 s)-1, leading to a net adduct decay time constant of 30 s at pH 8.
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Comparisons
Source-backed strengths
The domain has a defined mechanistic basis for dark-state recovery, specifically a base-catalyzed process. Its reduction midpoint potential has been measured at approximately -280 mV, and mutational analysis shows that nearby methionine substitutions can reproducibly shift this potential upward by as much as 40 mV.
Source:
Replacements of residues at different sites near the flavin by methionine consistently increase E 0 from its value of around 280 mV by up to 40 mV.
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Moreover, methionine introduction invariably impairs photoactivation efficiency and thus renders the resultant As LOV2 variants less light-sensitive.
Compared with AsLOV2
Avena sativa phototropin-1 LOV2 domain and AsLOV2 address a similar problem space because they share recombination, signaling.
Shared frame: same top-level item type; shared target processes: recombination, signaling; shared mechanisms: conformational uncaging, conformational_uncaging; same primary input modality: light
Relative tradeoffs: appears more independently replicated; may reduce component-count burden.
Compared with LHCII N-terminal domain
Avena sativa phototropin-1 LOV2 domain and LHCII N-terminal domain address a similar problem space because they share recombination, signaling.
Shared frame: same top-level item type; shared target processes: recombination, signaling; shared mechanisms: conformational uncaging, conformational_uncaging; same primary input modality: light
Strengths here: appears more independently replicated; looks easier to implement in practice.
Compared with light-harvesting complex II
Avena sativa phototropin-1 LOV2 domain and light-harvesting complex II address a similar problem space because they share recombination, signaling.
Shared frame: same top-level item type; shared target processes: recombination, signaling; shared mechanisms: conformational_uncaging; same primary input modality: light
Relative tradeoffs: appears more independently replicated.
Ranked Citations
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