ISSN:
1573-5028
Keywords:
Anabaena PCC 7120
;
carotenoid biosynthesis
;
ζ-carotene desaturase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract A DNA fragment which has been isolated previously from an Anabaena DNA expression library was subcloned. The corresponding protein was overexpressed in Escherichia coli. The recombinant enzyme was fully active in converting ζ-carotene into lycopene in vitro with neurosporene as an intermediate. A smaller fragment which still contained the active enzyme was sequenced. An open reading frame of 1497 bp was found coding for a protein consisting of 499 amino acids with the calculated molecular weight of 56 740. In a computer search of nucleotide sequences contained in the EMBL nucleotide sequence library, all the best-fitting comparisons were carotenoid desaturases. The highest similarity was found with the crtI phytoene desaturase genes of bacteria and the al-1 gene from Neurospora crassa. A much lower similarity was found with the pds genes coding for phytoene desaturase from cyanobacteria and higher plants. It is shown in protein similarity plots that the amino acid similarity of ζ-carotene desaturase to the latter is mainly limited to the N terminus of the polypeptides. In contrast, the protein similarity plots and a comparison of a conserved region clearly demonstrate that there is a strong relationship between ζ-carotene desaturase and the phytoene desaturases from various bacteria and fungi. Therefore we propose that the ζ-carotene desaturase gene is homologous to the crt I phytoene desaturase genes of bacteria and fungi.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00020174
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