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 zds-Fc, 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, zds-Fc showed high homology with previously described ζ-carotene desaturases from higher plant species (Al-Babili et al. 1998; Cong et al. 2009; Matthews et al. 2003; Yan et al. 2011). Additionally, sequence analysis revealed a high degree of conservation among plant ZDSs. The deduced ZDS protein, designated FcZDS, 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 zds-Fc as an integral part of the ZDS family of proteins.