Abstract
Carotene desaturation, an essential step in the carotenoid biosynthesis pathway, is catalyzed by two enzymes, phytoene desaturase (PDS) and ζ-carotene desaturase (zeta carotene desaturase, ZDS). Here we describe cloning and E. coli expression of zdsfc, a novel Ficus carica ζ-carotene desaturase catalyzing dehydrogenation of ζ-carotene into neurosporene and finally lycopene. The ζ-carotene desaturase (ZDS) gene was amplified from the fig tree by rapid amplification of cDNA ends (RACE) and spanned a 1746 bp open reading frame (ORF), encoding a protein of 582 amino acid residues with a predicted molecular weight of 64kD. The N-terminal region of this polypeptide contained a putative transit sequence for plastid targeting. By phylogenetic and sequence analyses, zdsfc showed high homology with previously described ζ-carotene desaturases from higher plant species [1-4]. Additionally, sequence analysis revealed a high degree of conservation among plant ZDSs. The deduced ZDS protein, designated zdsfc, also contains an N-terminus dinucleotide-binding, followed by a conserved region identified in other carotene desaturase sequences. These data, taken together, confirm our cloned zdsfc as an integral part of the ZDS family of proteins.
Highlights
Carotenoids are pigments synthetized by plants, fungi, bacteria, and algae with the main function of protecting them from the action of singlet oxygen and other radicals [5]
Since 1990, when cloned the carotenoid biosynthesis gene cluster from Erwinia uredovora, many carotenoid biosynthetic genes have been identified in plants and other organisms We have previously reported the production of β-carotene by expression of recombinant Ficus carica lycopene beta-cyclase in E. coli [13,14]
The amplified DNA was shown to span to the central area of zdsfc, and displayed a high similarity (80% to 83%) to other plant zeta-carotene desaturase genes, such as those from Citrus unshi (AB072343.1), Citrus maxima (EU798286.1), Malus x domestica (AF429983.1), Citrus sinensis (AJ319762.1), Jatropha curcas (GQ337075.1), Citrus x paradisi (AF372617.1), Fragaria x ananassa (FJ795343.1), Carica papaya (FJ812088.1) and Daucus carota (DQ192189.1)
Summary
Carotenoids are pigments synthetized by plants, fungi, bacteria, and algae with the main function of protecting them from the action of singlet oxygen and other radicals [5]. Carotenoids can function as regulators of plant growth and development, as accessory pigments in photosynthesis, as photoprotectors preventing photo-oxidative damage, or as precursors to the hormone abscisic acid (ABA) [6]. They are responsible for the color of fruits and flowers, generating distinct yellow, orange, and red colors, substantially contributing to plant-animal communication [6,7]. The colors of many carotenoid-accumulating fruits and flowers increase their appeal and their economic value [8,9] These pigments play an important protective role, in human and animal diets, as antioxidants
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