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Isolation and characterization of a lycopene ε-cyclase gene of Chlorella (Chromochloris) zofingiensis. Regulation of the carotenogenic pathway by nitrogen and light.

Cordero BF, Couso I, Leon R, Rodriguez H, Vargas MA - Mar Drugs (2012)

Bottom Line: A single copy of Czlcy-e was found in C. zofingiensis.High irradiance stress did not increase mRNA levels of neither lycopene β-cyclase gene (lcy-b) nor lycopene ε-cyclase gene (lcy-e) as compared with low irradiance conditions, whereas the transcript levels of psy, pds, chyB and bkt genes were enhanced, nevertheless triggering the synthesis of the secondary carotenoids astaxanthin, canthaxanthin and zeaxanthin and decreasing the levels of the primary carotenoids α-carotene, lutein, violaxanthin and β-carotene.The combined effect of both high light and nitrogen starvation stresses enhanced significantly the accumulation of these carotenoids as well as the transcript levels of bkt gene, as compared with the effect of only high irradiance stress.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant Biochemistry and Photosynthesis, CIC Cartuja, University of Seville and CSIC, Avda. Americo Vespucio, n° 49, Seville 41092, Spain. baldomero@ibvf.csic.es

ABSTRACT
The isolation and characterization of the lycopene ε-cyclase gene from the green microalga Chlorella (Chromochloris) zofingiensis (Czlcy-e) was performed. This gene is involved in the formation of the carotenoids α-carotene and lutein. Czlcy-e gene encoded a polypeptide of 654 amino acids. A single copy of Czlcy-e was found in C. zofingiensis. Functional analysis by heterologous complementation in Escherichia coli showed the ability of this protein to convert lycopene to δ-carotene. In addition, the regulation of the carotenogenic pathway by light and nitrogen was also studied in C. zofingiensis. High irradiance stress did not increase mRNA levels of neither lycopene β-cyclase gene (lcy-b) nor lycopene ε-cyclase gene (lcy-e) as compared with low irradiance conditions, whereas the transcript levels of psy, pds, chyB and bkt genes were enhanced, nevertheless triggering the synthesis of the secondary carotenoids astaxanthin, canthaxanthin and zeaxanthin and decreasing the levels of the primary carotenoids α-carotene, lutein, violaxanthin and β-carotene. Nitrogen starvation per se enhanced mRNA levels of all genes considered, except lcy-e and pds, but did not trigger the synthesis of astaxanthin, canthaxanthin nor zeaxanthin. The combined effect of both high light and nitrogen starvation stresses enhanced significantly the accumulation of these carotenoids as well as the transcript levels of bkt gene, as compared with the effect of only high irradiance stress.

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Effect of irradiance and nitrogen availability on the cellular content of lutein, violaxanthin, α-carotene, β-carotene, zeaxanthin, canthaxanthin and astaxanthin in C. zofingiensis. Culture conditions: low irradiance (20 µmol photons m−2 s−1) and nitrate replete (black line); low irradiance and nitrate deprivation (red line); high irradiance (300 µmol photons m−2 s−1) and nitrate replete (green line); high irradiance and nitrate deprivation (blue line). Carotenoids were identified as described in Experimental Section. Error bars indicate the standard deviations of four independent measurements. dw, dry weight.
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marinedrugs-10-02069-f007: Effect of irradiance and nitrogen availability on the cellular content of lutein, violaxanthin, α-carotene, β-carotene, zeaxanthin, canthaxanthin and astaxanthin in C. zofingiensis. Culture conditions: low irradiance (20 µmol photons m−2 s−1) and nitrate replete (black line); low irradiance and nitrate deprivation (red line); high irradiance (300 µmol photons m−2 s−1) and nitrate replete (green line); high irradiance and nitrate deprivation (blue line). Carotenoids were identified as described in Experimental Section. Error bars indicate the standard deviations of four independent measurements. dw, dry weight.

Mentions: With regard to cell primary carotenoid contents such as lutein, α-carotene, β-carotene and violaxanthin (Figure 7), they accumulated at low irradiance and enough nitrogen availability, cell contents decreasing at high irradiance and more significantly under conditions of both high irradiance and nitrogen starvation. An opposite trend was observed for secondary carotenoids, such as canthaxanthin, zeaxanthin and astaxanthin, their synthesis being triggered at high irradiance and the highest accumulations of these carotenoids being registered under conditions of nitrogen starvation. In addition, cells were lacking these carotenoids at low irradiance, regardless of the nitrogen availability. Total carotenoids and chlorophylls a and b contents showed a similar response than that registered for lutein under the different conditions studied (data not shown).


Isolation and characterization of a lycopene ε-cyclase gene of Chlorella (Chromochloris) zofingiensis. Regulation of the carotenogenic pathway by nitrogen and light.

Cordero BF, Couso I, Leon R, Rodriguez H, Vargas MA - Mar Drugs (2012)

Effect of irradiance and nitrogen availability on the cellular content of lutein, violaxanthin, α-carotene, β-carotene, zeaxanthin, canthaxanthin and astaxanthin in C. zofingiensis. Culture conditions: low irradiance (20 µmol photons m−2 s−1) and nitrate replete (black line); low irradiance and nitrate deprivation (red line); high irradiance (300 µmol photons m−2 s−1) and nitrate replete (green line); high irradiance and nitrate deprivation (blue line). Carotenoids were identified as described in Experimental Section. Error bars indicate the standard deviations of four independent measurements. dw, dry weight.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475274&req=5

marinedrugs-10-02069-f007: Effect of irradiance and nitrogen availability on the cellular content of lutein, violaxanthin, α-carotene, β-carotene, zeaxanthin, canthaxanthin and astaxanthin in C. zofingiensis. Culture conditions: low irradiance (20 µmol photons m−2 s−1) and nitrate replete (black line); low irradiance and nitrate deprivation (red line); high irradiance (300 µmol photons m−2 s−1) and nitrate replete (green line); high irradiance and nitrate deprivation (blue line). Carotenoids were identified as described in Experimental Section. Error bars indicate the standard deviations of four independent measurements. dw, dry weight.
Mentions: With regard to cell primary carotenoid contents such as lutein, α-carotene, β-carotene and violaxanthin (Figure 7), they accumulated at low irradiance and enough nitrogen availability, cell contents decreasing at high irradiance and more significantly under conditions of both high irradiance and nitrogen starvation. An opposite trend was observed for secondary carotenoids, such as canthaxanthin, zeaxanthin and astaxanthin, their synthesis being triggered at high irradiance and the highest accumulations of these carotenoids being registered under conditions of nitrogen starvation. In addition, cells were lacking these carotenoids at low irradiance, regardless of the nitrogen availability. Total carotenoids and chlorophylls a and b contents showed a similar response than that registered for lutein under the different conditions studied (data not shown).

Bottom Line: A single copy of Czlcy-e was found in C. zofingiensis.High irradiance stress did not increase mRNA levels of neither lycopene β-cyclase gene (lcy-b) nor lycopene ε-cyclase gene (lcy-e) as compared with low irradiance conditions, whereas the transcript levels of psy, pds, chyB and bkt genes were enhanced, nevertheless triggering the synthesis of the secondary carotenoids astaxanthin, canthaxanthin and zeaxanthin and decreasing the levels of the primary carotenoids α-carotene, lutein, violaxanthin and β-carotene.The combined effect of both high light and nitrogen starvation stresses enhanced significantly the accumulation of these carotenoids as well as the transcript levels of bkt gene, as compared with the effect of only high irradiance stress.

View Article: PubMed Central - PubMed

Affiliation: Institute of Plant Biochemistry and Photosynthesis, CIC Cartuja, University of Seville and CSIC, Avda. Americo Vespucio, n° 49, Seville 41092, Spain. baldomero@ibvf.csic.es

ABSTRACT
The isolation and characterization of the lycopene ε-cyclase gene from the green microalga Chlorella (Chromochloris) zofingiensis (Czlcy-e) was performed. This gene is involved in the formation of the carotenoids α-carotene and lutein. Czlcy-e gene encoded a polypeptide of 654 amino acids. A single copy of Czlcy-e was found in C. zofingiensis. Functional analysis by heterologous complementation in Escherichia coli showed the ability of this protein to convert lycopene to δ-carotene. In addition, the regulation of the carotenogenic pathway by light and nitrogen was also studied in C. zofingiensis. High irradiance stress did not increase mRNA levels of neither lycopene β-cyclase gene (lcy-b) nor lycopene ε-cyclase gene (lcy-e) as compared with low irradiance conditions, whereas the transcript levels of psy, pds, chyB and bkt genes were enhanced, nevertheless triggering the synthesis of the secondary carotenoids astaxanthin, canthaxanthin and zeaxanthin and decreasing the levels of the primary carotenoids α-carotene, lutein, violaxanthin and β-carotene. Nitrogen starvation per se enhanced mRNA levels of all genes considered, except lcy-e and pds, but did not trigger the synthesis of astaxanthin, canthaxanthin nor zeaxanthin. The combined effect of both high light and nitrogen starvation stresses enhanced significantly the accumulation of these carotenoids as well as the transcript levels of bkt gene, as compared with the effect of only high irradiance stress.

Show MeSH
Related in: MedlinePlus