Flavin‐based Blue‐light Photosensors: A Photobiophysics Update

Losi, Aba

doi:10.1111/j.1751-1097.2007.00196.x

Cited by 190 publications

(214 citation statements)

References 188 publications

(414 reference statements)

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“…4B. From this figure, a half-life of 15 min is calculated that is in the range of half-lives of other flavin-based sensory photoreceptors such as (12,28).…”

Section: Resultsmentioning

confidence: 99%

“…Currently, 3 classes of photosensory flavoproteins are known (12,28,31): Cryptochrome, LOV domain photoreceptors, and BLUF domain photoreceptors. Although CRY was the first flavin-based sensory photoreceptor to be discovered, more progress has been made in understanding the signaling mechanisms of LOV and BLUF proteins.…”

Section: Discussionmentioning

confidence: 99%

“…Currently, three types of photosensory flavoproteins are known (12): the photolyase/CRY family, the LOV domain proteins such as phototropin, and the BLUF domain proteins such as the photoactivated adenylyl cyclase. Whereas photolyase, as noted above, carries out catalysis by light-induced cyclic electron transfer, LOV and BLUF domain proteins initiate photosignaling by a lightinduced conformational change.…”

mentioning

confidence: 99%

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Reaction mechanism of Drosophila cryptochrome

Öztürk

Selby

Annayev

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

120

174

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Cryptochrome (CRY) is a blue-light sensitive flavoprotein that functions as the primary circadian photoreceptor in Drosophila melanogaster. The mechanism by which it transmits the light signal to the core clock circuitry is not known. We conducted in vitro studies on the light-induced conformational change in CRY and its effect on protein-protein interaction and performed in vivo analysis of the lifetime of the signaling state of the protein to gain some insight into the mechanism of phototransduction. We find that exposure of CRY to blue light induces a conformation similar to that of the constitutively active CRY mutant with a C-terminal deletion (CRYΔ). This light-induced conformation has a half-life of ∼15 min in the dark at 25°C and is characterized by increased affinity to Jetlag E3 ligase. In vivo analysis reveals that in the Drosophila S2 cell line, the signaling state induced by a millisecond light exposure has a half-life of 27 min in the dark at 0°C during which period it is susceptible to degradation by the ubiquitin-proteasome system. These findings lead to a plausible model for circadian photoreception/ phototransduction in Drosophila.circadian clock | photocycle | proteolysis | sensory flavoprotein C ryptochrome (CRY) is a flavoprotein that regulates growth and development in plants in response to blue light, functions as a circadian photoreceptor in Drosophila and other insects, and acts as a core component of the molecular clock in mammalian organisms (1-4). Despite extensive research on CRYs photosensory function in Arabidopsis and Drosophila, its mechanism of photoreception/phototransduction is poorly understood. Even the redox status of the FAD cofactor is a matter of some debate (5-8). In the phylogenetically related protein, DNA photolyase, photoinduced cyclic electron transfer from the FADH − cofactor to a pyrimidine photodimer repairs the DNA damage and regenerates the FADH − for new rounds of catalysis (9-11). However, there is no evidence so far for a similar reaction in either Arabidopsis CRY1 (AtCRY1) and CRY2 or Drosophila CRY, which at present are the most extensively studied CRYs. The lack of evidence for a cyclic redox reaction in CRYs has led to consideration of the mechanisms of other photosensory flavoproteins as potential models for CRYs in general and Drosophila CRY in particular.Currently, three types of photosensory flavoproteins are known (12): the photolyase/CRY family, the LOV domain proteins such as phototropin, and the BLUF domain proteins such as the photoactivated adenylyl cyclase. Whereas photolyase, as noted above, carries out catalysis by light-induced cyclic electron transfer, LOV and BLUF domain proteins initiate photosignaling by a lightinduced conformational change. Failing to obtain any evidence for CRY signaling by a photolyase-like mechanism, we considered the possibility that CRY also may carry out its light signaling by a light-induced conformational change that would affect the interaction of CRY with downstream signal transduction partners (13,14). Inde...

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“…4B. From this figure, a half-life of 15 min is calculated that is in the range of half-lives of other flavin-based sensory photoreceptors such as (12,28).…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Reaction mechanism of Drosophila cryptochrome

Öztürk

Selby

Annayev

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

120

174

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“…Their diverse properties make flavins of paramount importance for many biological systems. [1][2][3][4][5][6] For instance, flavins absorb in a wide spectral range from the optical up to the UV region, and their absorption maxima vary sensitively with structural modifications. In this way, flavincontaining domains act as light-harvesting modules in plants and algal phototropins and as blue-light receptors in fungals.…”

Section: Introductionmentioning

confidence: 99%

IRMPD spectroscopy of metalated flavins: structure and bonding of M^q+–lumichrome complexes (M^q+ = Li⁺–Cs⁺, Ag⁺, Mg²⁺)

Günther

Nieto

Berden

et al. 2014

Phys. Chem. Chem. Phys.

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Infrared multiphoton dissociation (IRMPD) spectra of mass selected isolated metal-lumichrome ionic complexes, M q+ LC n with M q+ = Li + , Na + , K + , Rb + , Cs + , Ag + (n = 1), and Mg 2+ (n = 2), are recorded in the fingerprint range. The complexes are generated in an electrospray ionization source coupled to an ion cyclotron mass spectrometer and the IR free electron laser FELIX. Vibrational and isomer assignments of the IRMPD spectra are accomplished by density functional theory calculations at the B3LYP/cc-pVDZ level, which provide insight into the structure, binding energy, bonding mechanism, and spectral properties of the complexes. The two major binding sites identified involve metal bonding to the oxygen atoms of the two available carbonyl groups of LC (denoted O2 and O4). The more stable O4 isomer benefits from an additional interaction with the lone pair of the nearby N5 atom of LC. While M + LC with alkali metals are mainly stabilized by electrostatic forces, the Ag + LC complex reveals additional stabilization arising from partly covalent contributions. Finally, the interaction of Mg 2+ ions with LC is largely enhanced by the doubled positive charge. The frequencies of the CQO stretching modes are a sensitive indicator of both the metal binding site and the metal bond strength.

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“…Currently, any protein with sequence homology to photolyase but with no repair function is called cryptochrome and is presumed to be a photosensory pigment (37)(38)(39)(40)(41). In A. thaliana, it has been shown conclusively that AtCRY1 and AtCRY2 function as blue-light photoreceptors (9).…”

Section: Cryptochromementioning

confidence: 99%