Blue protein with red fluorescence

Ghosh, Swagatha; Yu, Chung Huang; Ferraro, D.J.; Sudha, Sai; Pal, Samir Kumar; Schaefer, Wayne F.; Gibson, David T.; Ramaswamy, S.

doi:10.1073/pnas.1525622113

Cited by 35 publications

(58 citation statements)

References 55 publications

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“…This may not be the case for heterogeneous ligands and binding sites especially in situations where multimeric complexes are formed. For example lipocalins are known to form higher order oligomers [8–10]. For apolipoprotein-D, crustacyanin and β lactoglobulin the oligomeric state has been linked to ligand binding functions [11,12].…”

Section: Introductionmentioning

confidence: 99%

Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n)

Glasgow

Abduragimov

2018

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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The stoichiometry of a ligand binding reaction to a protein is given by a parameter (n). The value of this parameter may indicate the presence of protein monomer or dimers in the binding complex. Members of the lipocalin superfamily show variation in the stoichiometry of binding to ligands. In some cases the stoichiometry parameter (n) has been variously reported for the same protein as mono- and multimerization of the complex. Prime examples include retinol binding protein, β lactoglobulin and tear lipocalin, also called lipocalin-1(LCN1). Recent work demonstrated the stoichiometric ratio for ceramide:tear lipocalin varied (range n = 0.3-0.75) by several different methods. The structure of ceramide raises the intriguing possibility of a lipocalin dimer complex with each lipocalin molecule attached to one of the two alkyl chains of ceramide. The stoichiometry of the ceramide-tear lipocalin binding complex was explored in detail using size exclusion chromatography and time resolved fluorescence anisotropy. Both methods showed consistent results that tear lipocalin remains monomeric when bound to ceramide. Delipidation experiments suggest the most likely explanation is that the low 'n' values result from prior occupancy of the binding sites by native ligands. Lipocalins such as tear lipocalin that have numerous binding partners are particularly prone to an underestimated apparent stoichiometry parameter.

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Section: Introductionmentioning

confidence: 99%

Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n)

Glasgow

Abduragimov

2018

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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“…The resultant 15-kD monomer fluoresced modestly in the far-red spectrum (ex = 648 nm, em = 662 nm, F = 1.58%). This quantum yield is similar to sandercyanin, a naturally occurring fluorescent BV-binding fish pigment (F = 1.6%) 41 , and less than those of BV-binding directed evolution products derived from Bph-and AP (F ~ 7-18%) [17][18][19][20][21][22][23]31 . For simplicity, we hereon call this de novo-designed fluorescence-activating protein, "dFP."…”

Section: Rational Design and Construction Strategymentioning

confidence: 70%

Rational construction of compact de novo-designed biliverdin-binding proteins

Sheehan

Magaraci

Кузнецов

et al. 2018

Preprint

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We report the rational construction of a de novo-designed biliverdin-binding protein by first principles of protein design, informed by energy minimization modeling in Rosetta. The selfassembling tetrahelical bundles bind biliverdin IXa (BV) cofactor auto-catalytically in vitro, similar to photosensory proteins that bind BV (and related bilins, or linear tetrapyrroles) despite lacking sequence and structural homology to the natural counterparts. Upon identifying a suitable site for cofactor ligation to the protein scaffold, stepwise placement of residues stabilized BV within the hydrophobic core. Rosetta modeling was used in the absence of a high-resolution structure to define the structure-function of the binding pocket. Holoprotein formation indeed stabilized BV, resulting in increased far-red BV fluorescence. By removing segments extraneous to cofactor stabilization or bundle stability, the initial 15-kilodalton de novo-designed fluorescence-activating protein ("dFP") was truncated without altering its optical properties, down to a miniature 10kilodalton "mini," in which the protein scaffold extends only a half-heptad repeat beyond the hypothetical position of the bilin D-ring. This work demonstrates how highly compact holoprotein fluorochromes can be rationally constructed using de novo protein design technology and natural cofactors.

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“…This complex exhibits red fluorescence under UV light (λ ex 375 nm /λ em 675 nm). However, it is not known whether this complex and its fluorescence protect the fishes from harmful effects of UV radiation (Ghosh et al, 2016). Our study adds fluorescence in the tardigrade Paramacrobiotus sp.…”

Section: Discussionmentioning

confidence: 99%

Naturally occurring fluorescence protects the eutardigrade Paramacrobiotus sp. from ultraviolet radiation

Suma

Prakash

Giri

et al. 2019

Preprint

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Naturally occurring fluorescence has been observed in multiple species ranging from bacteria to birds. In macroscopic animals such as birds and fishes, fluorescence provides a visual communication signal. However, the functional significance of this phenomenon is not known in most cases. Though photoprotection is attributed to fluorescence under ultraviolet (UV) light in some organisms, it lacks direct experimental evidence. Here, we have identified a new species of eutardigrade belonging to the genus Paramacrobiotus, which exhibits fluorescence under UV light. Using a natural variant of the same species that lacks fluorescence, we show that the fluorescence confers tolerance to lethal UV radiation. Remarkably, we could transfer this property to UV-sensitive Hypsibius exemplaris, another eutardigrade, and also to C. elegans, a nematode. Using high performance liquid chromatography (HPLC) we isolated the fluorescent compound from Paramacrobiotus sp. This compound has excitation maxima (λex) at 370 nm and emission maxima (λem) at 420-430 nm. We propose that Paramacrobiotus sp. uses a fluorescent shield that absorbs harmful UV radiation, and emits harmless blue light, thereby protecting itself from the lethal effects of UV radiation.Summary statementTardigrades are well known for their tolerance to extreme environmental conditions. In this study, we have identified a new tardigrade species that employs a fluorescent shield to protect itself from the germicidal ultra violet radiation.

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Blue protein with red fluorescence

Cited by 35 publications

References 55 publications

Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n)

Ligand binding complexes in lipocalins: Underestimation of the stoichiometry parameter (n)

Rational construction of compact de novo-designed biliverdin-binding proteins

Naturally occurring fluorescence protects the eutardigrade Paramacrobiotus sp. from ultraviolet radiation

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