Resequencing of the Red Alga Cyanidioschyzon merolae: Strain Differences and Mitochondrial Sequence Corrections.
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ABSTRACT:
SUBMITTER: Sato N
PROVIDER: S-EPMC7291098 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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Resequencing of the Red Alga Cyanidioschyzon merolae: Strain Differences and Mitochondrial Sequence Corrections.
Sato Naoki N Moriyama Takashi T Mori-Moriyama Natsumi N
Microbiology resource announcements 20200611 24
Two laboratory strains of the red alga <i>Cyanidioschyzon merolae</i> 10D were resequenced. We found some strain differences in the nuclear and chloroplast genomes. We also identified corrections of the mitochondrial genome sequence. ...[more]
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Project description:Cyanidioschyzon merolae is considered to be one of the most primitive of eukaryotic photosynthetic organisms. To obtain insights into the origin and evolution of the pathway of carotenoid biosynthesis in eukaryotic plants, the carotenoid content of C. merolae was ascertained, genes encoding enzymes of carotenoid biosynthesis in this unicellular red alga were identified, and the activities of two candidate pathway enzymes of particular interest, lycopene cyclase and beta-carotene hydroxylase, were examined. C. merolae contains perhaps the simplest assortment of chlorophylls and carotenoids found in any eukaryotic photosynthetic organism: chlorophyll a, beta-carotene, and zeaxanthin. Carotenoids with epsilon-rings (e.g., lutein), found in many other red algae and in green algae and land plants, were not detected, and the lycopene cyclase of C. merolae quite specifically produced only beta-ringed carotenoids when provided with lycopene as the substrate in Escherichia coli. Lycopene beta-ring cyclases from several bacteria, cyanobacteria, and land plants also proved to be high-fidelity enzymes, whereas the structurally related epsilon-ring cyclases from several plant species were found to be less specific, yielding products with beta-rings as well as epsilon-rings. C. merolae lacks orthologs of genes that encode the two types of beta-carotene hydroxylase found in land plants, one a nonheme diiron oxygenase and the other a cytochrome P450. A C. merolae chloroplast gene specifies a polypeptide similar to members of a third class of beta-carotene hydroxylases, common in cyanobacteria, but this gene did not produce an active enzyme when expressed in E. coli. The identity of the C. merolae beta-carotene hydroxylase therefore remains uncertain.
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