Co-regulation of a gene homologous to early light-induced genes in higher plants and beta-carotene biosynthesis in the alga Dunaliella bardawil.
Dunaliella bardawil, a unicellular green alga that can be induced to accumulate massive amounts of beta-carotene, is particularly suitable for studies of carotenogenesis regulation and its links to developmental and adaptive processes in the chloroplast. A cDNA clone corresponding to a transcript accumulating coordinately with carotenogenesis induction was isolated by differential hybridization of a cDNA library made from intensely illuminated cells. This transcript was also abundant in algal mutants able to accumulate beta-carotene under relatively low light intensity. DNA sequence analysis indicates that cbr (for carotene biosynthesis-related) is closely related to early light-induced genes (elip) of higher plants. Similarity also exists between repeated oligopeptide motifs in Cbr and Cab proteins of photosystems I and II. Three upstream direct repeats in cbr include an octamer and hexamer related to mammalian sterol regulatory elements. The relationship between cbr transcript and beta-carotene accumulation, the structural similarity between Cbr and Cab proteins, and the presence of potential SRE-1 elements lead us to propose that Cbr represents novel carotenoid binding proteins, whose synthesis might be coordinated with carotenogenic enzymes via an evolutionary conserved regulatory mechanism.
Lers
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Biochemistry Department, Weizmann Institute of Science, Rehovot, Israel.
Levy
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H
Zamir
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D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002338:Carotenoids / Q000096:biosynthesis*; D000460:Chlorophyta / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008027:Light; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D012995:Solubility; D013431:Sulfates / Q000378:metabolism; D019207:beta Carotene
D004271:DNA, Fungal; D012333:RNA, Messenger; D013431:Sulfates; D019207:beta Carotene; D002338:Carotenoids