Structure of a flavin-binding plant photoreceptor domain: Insights into light-mediated signal transduction

Crosson, Sean; Moffat, Keith

doi:10.1073/pnas.051520298

Cited by 456 publications

(564 citation statements)

References 58 publications

(53 reference statements)

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“…Moreover, they proposed that it increases the intersystem crossing (ISC) rate by rapid generation of the reactive FMN triplet state, leading to a shortening of the FMN singlet excitedstate lifetime. These conclusions are consistent with several experimental studies, which state that the presence of the reactive cysteine at about 4 Å of the FMN [12,68,69] is responsible for a shortening of the singlet excited state lifetime and increase of the ISC rate by a factor of 2-3 as compared to FMN in solution [63,70] or cysteine-less mutants [71,72]. In this context, it is worth pointing out that in LOV domains an efficient ISC rate is crucial.…”

Section: Resultssupporting

confidence: 91%

Effect of computational methodology on the conformational dynamics of the protein photosensor LOV1 from Chlamydomonas reinhardtii

2011

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LOV domains are the light-sensitive protein domains of plant phototropins and bacteria. They photochemically form a covalent bond between a flavin mononucleotide (FMN) chromophore and a cysteine, attached to the apo-protein, upon irradiation with blue light, which triggers a signal in the adjacent kinase. Although their signaling state has been well characterized through experimental means, their signal transduction pathway as well as dark-state activity are generally only poorly understood. Here we show results from molecular dynamics simulations where we investigated the effect of thermostating and long-range electrostatics on the solution structure and dynamical behavior of the wild-type LOV1 domain from the green algae Chlamydomonas reinhardtii in the dark. We demonstrate that these computational issues can dramatically affect the conformational fluctuations of such protein domains by suppressing configurations far from equilibrium or destabilizing local configurations, leading to artificial changes of the protein secondary structure as well as the H-bond network formed by the amino acids and the FMN. By comparing our calculation results with recent experimental data, we show that the noninvasive thermostating strategy, where the protein solute is only indirectly coupled to the thermostat via the solvent, in conjunction with the particle-mesh Ewald technique, provides dark-state conformers, which are in consistency with experimental observations. Moreover, our calculations indicate that the LOV1 domains can alter the intersystem crossing rate and rate of adduct formation by adjusting the population distribution of these dark-state conformers. This might permit them to function as a modulator of the signal intensity under low light conditions.

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Section: Resultssupporting

confidence: 91%

Effect of computational methodology on the conformational dynamics of the protein photosensor LOV1 from Chlamydomonas reinhardtii

2011

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“…PAS domains are known to bind cofactors such as FAD, which enables the detection of redox levels (Taylor and Zhulin 1999). However, the putative PAS domains in AOD2 and AOD5 do not appear to be closely related to those known to bind FMN or FAD (Huala et al 1997;Crosson and Moffat 2001). PAS domains are also involved in homo-and heterodimerization of proteins.…”

Section: Discussionmentioning

confidence: 99%

Two Zinc-Cluster Transcription Factors Control Induction of Alternative Oxidase in Neurospora crassa

Chae

Nargang

Cleary³

et al. 2007

Genetics

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The alternative oxidase transfers electrons from ubiquinol to molecular oxygen, providing a mechanism for bypassing the later steps of the standard cytochrome-mediated electron transport chain. The enzyme is found in an array of organisms and in many cases is known to be produced in response to perturbations of the standard chain. Alternative oxidase is encoded in the nucleus but functions in the inner mitochondrial membrane. This implies the existence of a retrograde regulation pathway for communicating from the mitochondrion to the nucleus to induce alternative oxidase expression. Previous studies on alternative oxidase in fungi and plants have shown that a number of genes are required for expression of the enzyme, but the identity of these genes has remained elusive. By gene rescue we have now shown that the aod-2 and aod-5 genes of Neurospora crassa encode transcription factors of the zinc-cluster family. Electrophoretic mobility shift assays show that the DNA-binding domains of the AOD2 and AOD5 proteins act in tandem to bind a sequence element in the alternative oxidase gene promoter that is required for expression. Both proteins contain potential PAS domains near their C terminus, which are found primarily in proteins involved in signal transduction.

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“…21,22 Specifically, the side chain of a conserved glutamine residue within LOV2 (Gln 575 in Arabidopsis phot1) which forms hydrogen bonds with the FMN chromophore flips by 180° upon cysteinyl adduct formation 11,23,24 causing protein changes in the central b-sheet scaffold that forms contacts with the Ja-helix. 19,20 We have recently shown that mutation of the conserved glutamine to leucine (Q575L) attenuates light-induced autophosphorylation of Arabidopsis phot1 expressed in insect cells, 13 suggesting that this residue plays a role in transmitting the signal generated upon light-driven cysteinyl adduct formation from within LOV2 to protein changes at the LOV2 surface.…”

Section: Lov2 Signal Transmissionmentioning

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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Structure of a flavin-binding plant photoreceptor domain: Insights into light-mediated signal transduction

Cited by 456 publications

References 58 publications

Effect of computational methodology on the conformational dynamics of the protein photosensor LOV1 from Chlamydomonas reinhardtii

Effect of computational methodology on the conformational dynamics of the protein photosensor LOV1 from Chlamydomonas reinhardtii

Two Zinc-Cluster Transcription Factors Control Induction of Alternative Oxidase in Neurospora crassa

Phototropin Receptor Kinase Activation by Blue Light

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