Dinoflagellates cyclize squalene oxide to lanosterol

Giner, José‐Luis; Wünsche, Laurent; Andersen, Robert A.; Djerassi, Carl

doi:10.1016/0305-1978(91)90037-z

Cited by 24 publications

(35 citation statements)

References 12 publications

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“…In such a model in which the acetate-mevalonate pathway was common to algae and fungi, in module II, cycloartenol formation would precede lanosterol for thermodynamic reasons ( 3 ), and in module III, the sterol C24-methyltransferase reductases were recruited into a patchwork assembly of enzymatic reactions that recognize the same sterol template for catalysis. The presence of lanosterol synthases in some algae and land plants ( 36,(51)(52)(53) and the ⌬ 25 (27) olefi n pathway as the source of C 30 sterols of elongated side chains extending from C27 in dinofl agellates ( 32 ) is consistent with this proposal.…”

Section: H 3 ]Methioninesupporting

confidence: 72%

“…The major sterols in the sterol composition, ergosterol and 7-dehydroporiferasterol, were purifi ed by HPLC, and 1 HNMR analysis confi rmed their structure and C24 ␤ -methyl/ethyl group stereochemistry ( supplementary Table I ). Minor compounds detected in the GC chromatogram were identifi ed according to GC in a microsomal enzyme preparation converts exclusively to cycloartenol ( 36 ). On the other hand, information is lacking about the types and amount of C4 methyl-or C24(28)-ethylidene intermediates involved in the sequence of chemicals to ergosterol or its 24-ethyl homolog from which a reliable sterol biosynthesis pathway could be constructed.…”

Section: Total Sterols Of Wild-type Strainmentioning

confidence: 99%

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Evolutionarily conserved Δ25(27)-olefin ergosterol biosynthesis pathway in the alga Chlamydomonas reinhardtii

Miller

Haubrich

Wang

et al. 2012

Journal of Lipid Research

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Section: H 3 ]Methioninesupporting

confidence: 72%

Section: Total Sterols Of Wild-type Strainmentioning

confidence: 99%

Evolutionarily conserved Δ25(27)-olefin ergosterol biosynthesis pathway in the alga Chlamydomonas reinhardtii

Miller

Haubrich

Wang

et al. 2012

Journal of Lipid Research

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“…A deprotonation from C9 forms the 8,9-double bond of lanosterol whereas a deprotonation from C19 allows the cycloartenol cyclopropyl ring to close. Thus far, lanosterol synthase has been found only among the opisthokonts (animalsCfungiC choanozoa), trypanosomatids (Trypanosoma, Leishmania) and dinoflagellates (Giner et al 1991). All other eukaryotes that have been examined in this regard (at least members of the higher plants, green and red algae, amoebozoa, diatoms, euglenids and heterolobosea) make cycloartenol as their protosterol.…”

Section: Resultsmentioning

confidence: 99%

“…Dinoflagellates have also been reported to make lanosterol (Giner et al 1991), but no sequence information is currently available for their cyclases; they may represent a third instance of innovation, or may have acquired a lanosterol synthase laterally. It is as yet unclear which type, lanosterol synthase or cycloartenol synthase, was the ancestral form of OSC.…”

Section: Resultsmentioning

confidence: 99%

Steroids, triterpenoids and molecular oxygen

Summons

Bradley

Jahnke

et al. 2006

Phil. Trans. R. Soc. B

332

269

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There is a close connection between modern-day biosynthesis of particular triterpenoid biomarkers and presence of molecular oxygen in the environment. Thus, the detection of steroid and triterpenoid hydrocarbons far back in Earth history has been used to infer the antiquity of oxygenic photosynthesis. This prompts the question: were these compounds produced similarly in the past? In this paper, we address this question with a review of the current state of knowledge surrounding the oxygen requirement for steroid biosynthesis and phylogenetic patterns in the distribution of steroid and triterpenoid biosynthetic pathways.The hopanoid and steroid biosynthetic pathways are very highly conserved within the bacterial and eukaryotic domains, respectively. Bacteriohopanepolyols are produced by a wide range of bacteria, and are methylated in significant abundance at the C2 position by oxygen-producing cyanobacteria. On the other hand, sterol biosynthesis is sparsely distributed in distantly related bacterial taxa and the pathways do not produce the wide range of products that characterize eukaryotes. In particular, evidence for sterol biosynthesis by cyanobacteria appears flawed. Our experiments show that cyanobacterial cultures are easily contaminated by sterol-producing rust fungi, which can be eliminated by treatment with cycloheximide affording sterol-free samples.Sterols are ubiquitous features of eukaryotic membranes, and it appears likely that the initial steps in sterol biosynthesis were present in their modern form in the last common ancestor of eukaryotes. Eleven molecules of O 2 are required by four enzymes to produce one molecule of cholesterol. Thermodynamic arguments, optimization of function and parsimony all indicate that an ancestral anaerobic pathway is highly unlikely.The known geological record of molecular fossils, especially steranes and triterpanes, is notable for the limited number of structural motifs that have been observed. With a few exceptions, the carbon skeletons are the same as those found in the lipids of extant organisms and no demonstrably extinct structures have been reported. Furthermore, their patterns of occurrence over billion year time-scales correlate strongly with environments of deposition. Accordingly, biomarkers are excellent indicators of environmental conditions even though the taxonomic affinities of all biomarkers cannot be precisely specified. Biomarkers are ultimately tied to biochemicals with very specific functional properties, and interpretations of the biomarker record will benefit from increased understanding of the biological roles of geologically durable molecules.

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“…Second, among the microalgae, there are no reports of lanosterol in diatoms. Geiner et al (1991) reported that five species of dinoflagellates produced lanosterol. C 30 4-methyl steranes and C 26 norcholestanes are present in our oils and this supports a dinoflagellates origin for the lanostanes.…”

Section: Discussionmentioning

confidence: 99%