A Possible Trifunctional β-Carotene Synthase Gene Identified in the Draft Genome of Aurantiochytrium sp. Strain KH105

Iwasaka, Hiroaki; Koyanagi, Ryo; Satoh, Ryota; Nagano, Akiko; Watanabe, Kenshi; Hisata, Kanako; Satoh, Noriyuki; Aki, Tsunehiro

doi:10.3390/genes9040200

Cited by 34 publications

(19 citation statements)

References 47 publications

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“…The genes encoding for the enzymes of phytoene synthase (CrtB), phytoene desaturase (CrtI), and lycopene cyclase (CrtY), which are involved in the biosynthesis of β-carotene from GGPP, were found to be consecutively fused into an open reading frame without stop codons ( CrtIBY ). Similar CrtIBY genes were also found in five other Aurantiochytrium species, one of which was confirmed to catalyze β-carotene formation from GGPP [33]. The functional domains of CrtIBY of Aurantiochytrium sp.…”

Section: Resultssupporting

confidence: 56%

Illustrating and Enhancing the Biosynthesis of Astaxanthin and Docosahexaenoic Acid in Aurantiochytrium sp. SK4

Liu

et al. 2019

Marine Drugs

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The marine thraustochytrids are a promising source of docosahexaenoic acid (DHA) and the ketocarotenoid astaxanthin. In this study, the biosynthetic pathways of these two important metabolites in Aurantiochytrium sp. SK4 was illustrated by the analyses of the genome, transcriptome, key enzymes, and pathway products. Two sets of genes were involved in two pathways for the biosynthesis of fatty acids. The absence of Δ-15 desaturase genes and the presence of docosapentaenoic acid (DPA), up to 12% of total fatty acids suggest that Aurantiochytrium sp. SK4 may synthesize DHA mainly via a polyketide synthase (PKS) pathway. Three enzymes, namely geranyl diphosphate synthase (GPPS), farnysyl diphosphate synthase (FPPS), and geranylgeranyle diphosphate synthase (GGPPS) were found to be involved in the formation of GGPP that was subsequently catalyzed to β-carotene by a trifunctional CrtIBY enzyme. β-Carotene might be ketolated and then hydroxylated into astaxanthin based on the carotenoid profiles. The formation of GGPP was proposed to be the limiting steps for carotenoid production. Overexpression of the Archaeoglobus GPS together with the Escherichia coli isopentenyl pyrophosphate isomerase, and Vitreoscilla hemoglobin resulted in not only 1.85- and 5.02-fold increases of total carotenoids and astaxanthin, but also 2.40- and 2.74-fold increases of total fatty acids and DHA. This study provides insights into the biosynthesis of carotenoids and fatty acids in Aurantiochytrium.

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Section: Resultssupporting

confidence: 56%

Illustrating and Enhancing the Biosynthesis of Astaxanthin and Docosahexaenoic Acid in Aurantiochytrium sp. SK4

Liu

et al. 2019

Marine Drugs

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“…For example, there is four times more carotenoids in A. limacinum than in H. fermentalgiana, canthaxanthin being the dominant species in the former, whereas astaxanthin, canthaxanthin and βcarotene showed an equal distribution in the latter [6]. All the genes coding for the synthesis of astaxanthin from farnesyl pyrophosphate are identified in Aurantiochytrium, opening the route for metabolic engineering [112]. The synthesis of sterols from farnesyl pyrophosphate results in a very complex pathway because the various paths leading to the different classes of sterols often share common enzymatic steps and are therefore tightly interconnected.…”

Section: Carotenoids Sterols and Squalenementioning

confidence: 99%

The lipid metabolism in thraustochytrids

Morabito

Bournaud

Maës

et al. 2019

Progress in Lipid Research

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Thraustochytrids are unicellular heterotrophic marine protists of the Stramenopile group, often considered as non-photosynthetic microalgae. They have been isolated from a wide range of habitats including deep sea, but are mostly present in waters rich in sediments and organic materials. They are abundant in mangrove forests where they are major colonizers, feeding on decaying leaves and initiating the mangrove food web. Discovered 80 years ago, they have recently attracted considerable attention due to their biotechnological potential. This interest arises from their fast growth, their specific lipid metabolism and the improvement of the genetic tools and transformation techniques. These organisms are particularly rich in ω3-docosahexaenoic acid (DHA), an 'essential' fatty acid poorly encountered in land plants and animals but required for human health. To produce their DHA they use a complex system different from the classical fatty acid synthase system. They are also a potential source of squalene and carotenoids. Here we review our current knowledge about the life cycle, ecophysiology, and metabolism of these organisms, with a particular focus on lipid dynamics. We describe the different pathways involved in lipid and fatty acid syntheses, emphasizing their specificity, and we report on the recent efforts aimed to engineer their lipid metabolism.

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“…KH105 (accession BBB35234.1). This enzyme is coded by crtIBY , a gene that has been reported also in the genomes of other thraustochytrids [ 24 ].…”

Section: Resultsmentioning

confidence: 99%

Antarctic Thraustochytrids as Sources of Carotenoids and High-Value Fatty Acids

et al. 2021

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Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and carotenoids are needed as human dietary supplements and are essential components in commercial feeds for the production of aquacultured seafood. Microorganisms such as thraustochytrids are potential natural sources of these compounds. This research reports on the lipid and carotenoid production capacity of thraustochytrids that were isolated from coastal waters of Antarctica. Of the 22 isolates, 21 produced lipids containing EPA+DHA, and the amount of these fatty acids exceeded 20% of the total fatty acids in 12 isolates. Ten isolates were shown to produce carotenoids (27.4–63.9 μg/g dry biomass). The isolate RT2316-16, identified as Thraustochytrium sp., was the best producer of biomass (7.2 g/L in five days) rich in carotenoids (63.9 μg/g) and, therefore, became the focus of this investigation. The main carotenoids in RT2316-16 were β-carotene and canthaxanthin. The content of EPA+DHA in the total lipids (34 ± 3% w/w in dry biomass) depended on the stage of growth of RT2316-16. Lipid and carotenoid content of the biomass and its concentration could be enhanced by modifying the composition of the culture medium. The estimated genome size of RT2316-16 was 44 Mb. Of the 5656 genes predicted from the genome, 4559 were annotated. These included genes of most of the enzymes in the elongation and desaturation pathway of synthesis of ω-3 polyunsaturated fatty acids. Carotenoid precursors in RT2316-16 were synthesized through the mevalonate pathway. A β-carotene synthase gene, with a different domain organization compared to the gene in other thraustochytrids, explained the carotenoid profile of RT2316-16.

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A Possible Trifunctional β-Carotene Synthase Gene Identified in the Draft Genome of Aurantiochytrium sp. Strain KH105

Cited by 34 publications

References 47 publications

Illustrating and Enhancing the Biosynthesis of Astaxanthin and Docosahexaenoic Acid in Aurantiochytrium sp. SK4

Illustrating and Enhancing the Biosynthesis of Astaxanthin and Docosahexaenoic Acid in Aurantiochytrium sp. SK4

The lipid metabolism in thraustochytrids

Antarctic Thraustochytrids as Sources of Carotenoids and High-Value Fatty Acids

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