Evolutionary implications of the mosaic pyrimidine-biosynthetic pathway in eukaryotes

Nara, Takeshi; Hshimoto, Tetsuo; Aoki, Takashi

doi:10.1016/s0378-1119(00)00411-x

Cited by 90 publications

(74 citation statements)

References 15 publications

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“…There are other examples of similar division and diversification of enzymological capacities within key genes for pyrimidine (37), diterpene (38), and triterpene (39) metabolism. For instance, biosynthesis of the diterpene kaurene in many fungi relies on a single, multifunctional enzyme (40) that catalyzes the conversion of the linear isoprenoid intermediate geranylgeranyl diphosphate to the bicyclic copalyl diphosphate (CPP) product.…”

Section: Discussionmentioning

confidence: 99%

Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii

Niehaus

Okada

Devarenne

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

135

153

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Botryococcene biosynthesis is thought to resemble that of squalene, a metabolite essential for sterol metabolism in all eukaryotes. Squalene arises from an initial condensation of two molecules of farnesyl diphosphate (FPP) to form presqualene diphosphate (PSPP), which then undergoes a reductive rearrangement to form squalene. In principle, botryococcene could arise from an alternative rearrangement of the presqualene intermediate. Because of these proposed similarities, we predicted that a botryococcene synthase would resemble squalene synthase and hence isolated squalene synthase-like genes from Botryococcus braunii race B. While B. braunii does harbor at least one typical squalene synthase, none of the other three squalene synthase-like (SSL) genes encodes for botryococcene biosynthesis directly. SSL-1 catalyzes the biosynthesis of PSPP and SSL-2 the biosynthesis of bisfarnesyl ether, while SSL-3 does not appear able to directly utilize FPP as a substrate. However, when combinations of the synthase-like enzymes were mixed together, in vivo and in vitro, robust botryococcene (SSL-1+SSL-3) or squalene biosynthesis (SSL1+SSL-2) was observed. These findings were unexpected because squalene synthase, an ancient and likely progenitor to the other Botryococcus triterpene synthases, catalyzes a two-step reaction within a single enzyme unit without intermediate release, yet in B. braunii, these activities appear to have separated and evolved interdependently for specialized triterpene oil production greater than 500 MYA. Coexpression of the SSL-1 and SSL-3 genes in different configurations, as independent genes, as gene fusions, or targeted to intracellular membranes, also demonstrate the potential for engineering even greater efficiencies of botryococcene biosynthesis.algae | biofuels | terpene enzymology

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Section: Discussionmentioning

confidence: 99%

Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii

Niehaus

Okada

Devarenne

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

135

153

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“…Besides concentrating inorganic carbon for lipogenesis in plastids, CA may participate in other plastidial carboxylation reactions, such as carbamoyl phosphate synthetase (a plastid-localized enzyme in higher plants; Nara et al, 2000), which synthesizes the precursor for pyrimidine biosynthesis. Also, Kavroulakis et al (2000) have suggested that CA facilitates the recycling of CO 2 in developing soybean (Glycine max) root nodules during early stages of development.…”

Section: Discussionmentioning

confidence: 99%

Biochemical and Molecular Inhibition of Plastidial Carbonic Anhydrase Reduces the Incorporation of Acetate into Lipids in Cotton Embryos and Tobacco Cell Suspensions and Leaves

Hoang

Chapman

2002

Plant Physiology

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Two cDNAs encoding functional carbonic anhydrase (CA) enzymes were recently isolated from a non-photosynthetic, cotyledon library of cotton (Gossypium hirsutum) seedlings with putative plastid-targeting sequences (GenBank accession nos. AF132854 and AF132855). Relative CA transcript abundance and enzyme activity increased 9 and 15 times, respectively, in cotton embryos during the maximum period of reserve oil accumulation. Specific sulfonamide inhibitors of CA activity significantly reduced the rate of [ 14 C]acetate incorporation into total lipids in cotton embryos in vivo, and in embryo plastids in vitro, suggesting a role for CA in plastid lipid biosynthesis. CA inhibitors did not affect acetyl-coenzyme A carboxylase activity or total storage protein synthesis. Similar results were obtained for two other plant systems: cell suspensions (and isolated plastids therefrom) of tobacco (Nicotiana tabacum), and chloroplasts isolated from leaves of transgenic CA antisensesuppressed tobacco plants (5% of wild-type CA activity). In addition, tobacco cell suspensions treated with the CA inhibitor ethoxyzolamide showed a substantial loss of CO 2 compared with controls. The rate of [ 14 C]acetate incorporation into lipid in cell suspensions was reduced by limiting external [CO 2 ] (scrubbed air), and this rate was further reduced in the presence of ethoxyzolamide. Together, these results indicate that a reduction of CA activity (biochemical or molecular inhibition) impacts the rate of plant lipid biosynthesis from acetate, perhaps by impairing the ability of CA to efficiently "trap" inorganic carbon inside plastids for utilization by acetyl-coenzyme A carboxylase and the fatty acid synthesis machinery.Carbonic anhydrase (CA, EC 4.2.1.1) is a zinccontaining metalloenzyme that catalyzes the reversible hydration of CO 2 to HCO 3 Ϫ . The widespread abundance of CA isoforms in plants, animals, and microorganisms suggest that this enzyme has many diverse roles in biological processes. CA plays a critical role in biological systems because CO 2 gas is the membrane permeable form of inorganic carbon for cells, and, in general, the uncatalyzed interconversion between HCO 3 Ϫ and CO 2 is slow when compared with the required rate in living cells (Badger and Price, 1994).In photosynthetic organisms, one generally accepted physiological role of CA is to provide sufficient levels of inorganic carbon as part of a CO 2 -concentrating mechanism for improved photosynthetic efficiency. In Chlamydomonas reinhardtii, Badger and Price (1992) suggested that chloroplastic CA plays a role in photosynthetic carbon assimilation by converting accumulated pools of HCO 3 Ϫ to CO 2 , which is the substrate for Rubisco. Moroney et al. (1985) revealed that the reduction of periplasmic CA activity by using CAspecific inhibitors significantly reduced the efficiency of external inorganic carbon utilization for photosynthesis. Like green algae, CA in cyanobacteria plays an important role in the CO 2 -concentrating mechanism and in photosynthesis (Badger an...

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“…URA1 is the best-supported horizontal gene candidate in S. cerevisiae, and ura1⌬ cells present an identifiable phenotype. Previous work by Nara et al speculated that URA1 might be horizontally transferred (36); as URA1 from S. cerevisiae was the only fungal sequence included in their analysis insufficient data were provided to support this speculation. Further supporting evidence for a bacterial origin of URA1 has been reported based on sequences from Saccharomyces kluyveri (17,58).…”

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confidence: 95%

Contribution of Horizontal Gene Transfer to the Evolution of Saccharomyces cerevisiae

2005

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The genomes of the hemiascomycetes Saccharomyces cerevisiae and Ashbya gossypii have been completely sequenced, allowing a comparative analysis of these two genomes, which reveals that a small number of genes appear to have entered these genomes as a result of horizontal gene transfer from bacterial sources. One potential case of horizontal gene transfer in A. gossypii and 10 potential cases in S. cerevisiae were identified, of which two were investigated further. One gene, encoding the enzyme dihydroorotate dehydrogenase (DHOD), is potentially a case of horizontal gene transfer, as shown by sequencing of this gene from additional bacterial and fungal species to generate sufficient data to construct a well-supported phylogeny. The DHODencoding gene found in S. cerevisiae, URA1 (YKL216W), appears to have entered the Saccharomycetaceae after the divergence of the S. cerevisiae lineage from the Candida albicans lineage and possibly since the divergence from the A. gossypii lineage. This gene appears to have come from the Lactobacillales, and following its acquisition the endogenous eukaryotic DHOD gene was lost. It was also shown that the bacterially derived horizontally transferred DHOD is required for anaerobic synthesis of uracil in S. cerevisiae. The other gene discussed in detail is BDS1, an aryl-and alkyl-sulfatase gene of bacterial origin that we have shown allows utilization of sulfate from several organic sources. Among the eukaryotes, this gene is found in S. cerevisiae and Saccharomyces bayanus and appears to derive from the alpha-proteobacteria.

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Evolutionary implications of the mosaic pyrimidine-biosynthetic pathway in eukaryotes

Cited by 90 publications

References 15 publications

Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii

Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii

Biochemical and Molecular Inhibition of Plastidial Carbonic Anhydrase Reduces the Incorporation of Acetate into Lipids in Cotton Embryos and Tobacco Cell Suspensions and Leaves

Contribution of Horizontal Gene Transfer to the Evolution of Saccharomyces cerevisiae

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