LOV (light, oxygen, or voltage) domains of the blue-light photoreceptor phototropin (nph1): Binding sites for the chromophore flavin mononucleotide

Christie, John M.; Salomon, Michael; Nozue, Kazunari; Wada, Masamitsu; Briggs, Winslow R.

doi:10.1073/pnas.96.15.8779

Cited by 535 publications

(492 citation statements)

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“…After activation by light, phototropins undergo rapid photocycles (from seconds to minutes) and return to the dark state, so that they can be repeatedly activated by light (Christie et al 1999;Salomon et al 2000;Briggs and Christie 2002;Harper et al 2003). Since only a small portion of the WCC purified from the insect cells contained FAD, this prevented us from carrying out further photochemical analysis of the complex in vitro.…”

Section: Wcc Purified From Neurospora Does Not Have An Active Photocymentioning

confidence: 99%

“…Phototropins, the plant blue-light photoreceptors mediating phototropism, are the best photochemically and structurally studied LOV-domain-containing photoreceptors (Briggs and Huala 1999;Christie et al 1999;Crosson and Moffat 2001;Harper et al 2003;Christie and Briggs 2005). Like many other photoreceptors, phototropins undergo rapid photocycles in the dark after their light activation to return to the dark state (Salomon et al 2000), so that they can be repeatedly activated by light.…”

mentioning

confidence: 99%

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Molecular mechanism of light responses in Neurospora: from light-induced transcription to photoadaptation

He¹,

Liu²

2005

Genes Dev.

190

237

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Section: Wcc Purified From Neurospora Does Not Have An Active Photocymentioning

confidence: 99%

mentioning

confidence: 99%

Molecular mechanism of light responses in Neurospora: from light-induced transcription to photoadaptation

He¹,

Liu²

2005

Genes Dev.

190

237

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“…[1][2][3] The N-terminal photosensory region comprises two LOV domains each of which binds the blue light absorbing cofactor flavin mononucleotide (FMN) as chromophore. 4,5 LOV domains exhibit significant homology to motifs found in a diverse range of eukaryotic and prokaryotic proteins involved in sensing Light, Oxygen or Voltage, hence the acronym LOV. 6 Bacterially expressed LOV domains are photochemically reactive as monitored by absorbance spectroscopy.…”

Section: Light-induced Activation Of Phot1mentioning

confidence: 99%

Phototropin Receptor Kinase Activation by Blue Light

Jones

Christie

2008

Plant Signaling & Behavior

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Phototropins (phot1 and phot2) are blue light-activated serine/ threonine protein kinases that function to mediate a variety of adaptive processes that serve to optimize the photosynthetic efficiency of plants and thereby promote their growth. Light sensing by the phototropins is mediated by a repeated motif located within the N-terminal region of the protein designated the LOV domain. Although phototropins possess two LOV photosensors (LOV1 and LOV2), recent biophysical and structure-function analyses clearly indicate that the LOV2 domain plays a predominant role in regulating phototropin kinase activity owing to specific protein changes that occur in response to LOV2 photoexcitation. In particular, the central b-sheet scaffold plays a role in propagating the photochemical signal generated from within LOV2 to protein changes at the surface that are necessary for kinase activation. Light-Induced Activation of Phot1The primary amino acid structures of plant phototropins (phot1 and phot2) can be separated into two distinct regions: a N-terminal photosensory region linked to a C-terminal effector domain that includes a classic serine/threonine kinase motif. [1][2][3] The N-terminal photosensory region comprises two LOV domains each of which binds the blue light absorbing cofactor flavin mononucleotide (FMN) as chromophore. 4,5 LOV domains exhibit significant homology to motifs found in a diverse range of eukaryotic and prokaryotic proteins involved in sensing Light, Oxygen or Voltage, hence the acronym LOV. 6 Bacterially expressed LOV domains are photochemically reactive as monitored by absorbance spectroscopy. 7 In the dark, LOV domains bind FMN non-covalently forming a spectral species, LOV 447 , which absorbs maximally near 447 nm. 7,8 Irradiation of the domain induces the formation of a covalent bond between the C(4a) carbon of the FMN and the sulfur atom of a nearby, conserved cysteine residue within the domain. Cysteinyl adduct formation occurs within microseconds of illumination and produces a spectral species, LOV 390 , that absorbs maximally near 390 nm. 8 Mutation of the afore-mentioned active-site cysteine to either alanine or serine results in a loss of photochemical reactivity of the LOV domain. 7,8 Moreover, this mutation has been used successfully to probe the roles of LOV1 and LOV2 in regulating phototropin activity and function. [9][10][11][12] As reported previously (ref. 13), the Cys → Ala mutation within LOV2 of Arabidopsis thaliana phot1 (C517A) results in a loss of light-induced receptor autophosphorylation when expressed in insect cells (Fig. 1A), demonstrating that LOV2 is the principle photosensor regulating phot1 kinase activity. A similar mode of action has been reported for the LOV2 domain of Arabidopsis phot2. 12,14,15 The LOV1 domain, by contrast, is proposed to mediate receptor dimerization 16 and/or modulate the photoreactivity of LOV2. 14 Substitution of the conserved active-site cysteine with methionine has been shown to result in the formation of a unique photoproduct species abso...

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“…2 LOV domains consist of approximately 100 amino acids and noncovalently bind a single flavin. 3,4 Blue-light absorption initiates a photochemical reaction which results in the formation of a covalent adduct between a conserved cysteine and the flavin. 5,6 It is believed that this species, referred to as S 390 given its absorption band in the near-UV, corresponds to the signaling state of the protein.…”

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The LOV2 Domain of Phototropin: A Reversible Photochromic Switch

et al. 2004

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Light, oxygen, or voltage (LOV) domains constitute a new class of chromoprotein modules. 1 They form the blue-light-sensitive loci of the phototropins, a recently discovered class of plant photoreceptors that regulate a variety of responses. 2 LOV domains consist of approximately 100 amino acids and noncovalently bind a single flavin. 3,4 Blue-light absorption initiates a photochemical reaction which results in the formation of a covalent adduct between a conserved cysteine and the flavin. 5,6 It is believed that this species, referred to as S 390 given its absorption band in the near-UV, corresponds to the signaling state of the protein. The lifetime of the adduct in various LOV domains ranges from minutes to hours, 5,7-9 which implies that even under physiological illumination, there is a high probability for absorption of a second, near-UV photon. The resulting photochemistry in the LOV domain may have important consequences for its signaling function. For this reason, we have undertaken a time-resolved study of the molecular events that follow photolysis of S 390 in the LOV2 domain from the phy3 receptor of Adiantum.LOV2 was expressed and purified and transient absorption spectroscopy was carried out as previously described. 4,10 Continuous blue-light background illumination was applied to photoaccumulate S 390 , resulting in a steady-state S 390 population of about 85%. The remaining 15% can be assumed in the dark ground state D 447 , because the other photocycle intermediate, the FMN triplet, has a lifetime of only 2 µs 5 and will have a negligible concentration at steady state. The photoaccumulated sample was photolyzed with flashes of 100 fs duration at 400 nm, and the absorption changes were probed with a flash of white light at time delays ranging from -2 ps to 4.5 ns. To determine the dynamics of D 447 , we performed an experiment without background illumination but otherwise identical conditions. The resulting spectra were weighted and subtracted from the illuminated dataset. The resulting time-resolved spectra were subjected to a global analysis program 11 using a kinetic model consisting of sequentially interconverting species, that is, 1 f 2 f 3 f . . . , in which the arrows indicate successive monoexponential decays of increasing time constants. Associated with each species is a lifetime and a difference spectrum, denoted the species-associated difference spectrum (SADS). The results are shown in Figure 1. Four kinetic components are required to describe the data, with time constants of 500 fs, 9 ps, and 100 ps and a nondecaying component. The initially created excited species has a lifetime of 500 fs. The first SADS (thin solid line) representing this species shows a negative signal near 430 nm, which can be assigned to a combination of ground-state bleaching of the adduct and stimulated emission from the excited to the ground state. At wavelengths longer than 450 nm, it features an intense absorption with a maximum at 605 nm. We assign this SADS to the singlet excited state of S 390 . This spe...

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LOV (light, oxygen, or voltage) domains of the blue-light photoreceptor phototropin (nph1): Binding sites for the chromophore flavin mononucleotide

Cited by 535 publications

References 40 publications

Molecular mechanism of light responses in Neurospora: from light-induced transcription to photoadaptation

Molecular mechanism of light responses in Neurospora: from light-induced transcription to photoadaptation

Phototropin Receptor Kinase Activation by Blue Light

The LOV2 Domain of Phototropin: A Reversible Photochromic Switch

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