Disease relevance of C13433

• Molecular cloning of violaxanthin de-epoxidase from romaine lettuce and expression in Escherichia coli [1].
• Dehydration of these plants resulted in a 4-8-fold increase in abscisic acid and a decrease in antheraxanthin, violaxanthin and neoxanthin, but no change in beta-carotene or lutein plus zeaxanthin levels [2].

High impact information on C13433

• Wild-type tomato (Solanum lycopersicum) flowers are intensely yellow due to accumulation of the xanthophylls neoxanthin and violaxanthin [3].
• Genetic mapping, DNA sequencing, and complementation of npq1 demonstrated that this mutation affects the structural gene encoding violaxanthin deepoxidase [4].
• The npq1 mutant exhibited greatly reduced nonphotochemical quenching, demonstrating that violaxanthin deepoxidation is required for the bulk of rapidly reversible nonphotochemical quenching in Arabidopsis [4].
• Our results demonstrate that the violaxanthin cycle specifically protects thylakoid membrane lipids against photooxidation [5].
• Under consideration of former studies with Lhcb1 and Lhca proteins, the data imply that violaxanthin bound to the V1 and N1 binding site of antenna proteins is easily accessible for de-epoxidation in all antenna proteins, whereas violaxanthin bound to L2 is either only slowly or not convertible to zeaxanthin, depending on the respective protein [6].

Chemical compound and disease context of C13433

• We have used recombinant CP29 protein, over-expressed in Escherichia coli and refolded in vitro with purified pigments, to obtain a protein indistinguishable from the native complex extracted from thylakoids, binding either violaxanthin or zeaxanthin together with lutein [7].

Biological context of C13433

• The npq4 mutant, which possesses a normal violaxanthin cycle but has a limited capacity of quenching singlet excited chlorophylls, was rather tolerant to lipid peroxidation [5].
• Former studies with recombinant Lhcb1 and different Lhca proteins implied that each antenna protein contributes specifically to violaxanthin conversion related to protein-specific affinities of the different violaxanthin binding sites [6].
• In particular, violaxanthin bound to Lhcb4 was nearly inconvertible for de-epoxidation, whereas violaxanthin bound to Lhcb5 was fully convertible but with slow kinetics [6].
• The faster lifetime is due to energy transfer from a vibrationally unrelaxed S(1) state, whereas the 8- to 20-ps component is due to a transfer from the S(1,0) state of violaxanthin and/or neoxanthin located in site L2 [8].
• It has a major role in photosynthesis, acting in the Mehler peroxidase reaction with ascorbate peroxidase to regulate the redox state of photosynthetic electron carriers and as a cofactor for violaxanthin de-epoxidase, an enzyme involved in xanthophyll cycle-mediated photoprotection [9].

Anatomical context of C13433

• The resonance Raman spectra of violaxanthin and zeaxanthin in intact thylakoid membranes was determined [10].
• Carotenoid biosynthesis in vitro conversion of violaxanthin to capsorubin by a chromoplast enriched fraction of Capsicum fruits [11].
• The difuranoid auroxanthin encountered in the egg yolk was ascribed to violaxanthin and/or its furanoid derivatives present in the seaweed meal [12].

Associations of C13433 with other chemical compounds

• We have analyzed the efficiency of different Lhc proteins to exchange violaxanthin with zeaxanthin both in vivo and in vitro [13].
• Recombinant proteins were reconstituted with different xanthophyll mixtures to study the conversion of violaxanthin at different xanthophyll binding sites in these proteins [6].
• Carotenoid specificity of light-harvesting complex II binding sites. Occurrence of 9-cis-violaxanthin in the neoxanthin-binding site in the parasitic angiosperm Cuscuta reflexa [14].
• The enzyme responsible for the conversion of violaxanthin to zeaxanthin is violaxanthin de-epoxidase, which is located in the thylakoid lumen, is activated by low pH, and has been shown to use ascorbate (vitamin C) as its reductant in vitro [15].
• In this study, we have examined the influence of different lipids on the solubility of the xanthophyll cycle pigments diadinoxanthin (Ddx) and violaxanthin (Vx) and on the efficiency of Ddx and Vx de-epoxidation by the enzymes Vx de-epoxidase (VDE) from wheat and Ddx de-epoxidase (DDE) from the diatom Cyclotella meneghiniana, respectively [16].

Gene context of C13433

• The npq1 exhibited low antheraxanthin and zeaxanthin and high violaxanthin levels and the uncoupler-sensitive amplitudes of short (< 1 ns) PS II Chl a fluorescence distribution modes were strongly inhibited compared to the WT [17].
• Xanthophyll cycle-dependent nonphotochemical quenching in Photosystem II: Mechanistic insights gained from Arabidopsis thaliana L. mutants that lack violaxanthin deepoxidase activity and/or lutein [17].
• Simultaneously, the concentrations of violaxanthin, beta-carotene, ascorbate, alpha-tocopherol, and glutathione reductase activity progressively decreased [18].
• Sequence analyses of both violaxanthin de-epoxidase and zeaxanthin epoxidase establish the xanthophyll cycle enzymes as members of the lipocalin family of proteins [19].
• The newly identified, possibly redox-regulated proteins include: violaxanthin de-epoxidase, two oxygen-evolving enhancer proteins, carbonic anhydrase, photosystem I reaction center subunit N, photosystem I subunit III, S-adenosyl-L-methionine carboxyl methyltransferase, guanylate kinase, and bacterial mutT homolog [20].

Analytical, diagnostic and therapeutic context of C13433

• The L1 and L2 sites, localized by electron crystallography in the helix A/helix B cross, have the highest affinity for lutein, but also bind violaxanthin and zeaxanthin with lower affinity [21].
• From HPLC, the wild type (WT) monomer contains two luteins (Ls), one neoxanthin (N), and a trace of violaxanthin (V) per 12 Chls [22].
• Employing isocratic and gradient-elution high-performance liquid chromatography (HPLC) a number of straight-chain fatty acid esters (decanoate, laurate, myristate, palmitate) of violaxanthin, auroxanthin, lutein, zeaxanthin, isozeaxanthin, and beta-cryptoxanthin, prepared by partial synthesis, have been separated on a C18 reversed-phase column [23].
• The separation and the simultaneous determination of beta-carotene, cantaxanthin, lutein, violaxanthin and neoxanthin was accomplished using thin-layer chromatography on Chromarods, flame ionization detection and a two-stage development technique [24].
• The analysis of the electronic absorption spectra of LHCII and the FTIR spectra of the protein in the Amid I band spectral region indicates that violaxanthin isomerization is associated with the disaggregation of the complex [25].

References