Ergosterol, the unusual dominant sterol of the pythiaceous fungus Zoophagus insidians

Warner, Steven A.; Sovocool, G. Wayne; Domnas, A.

doi:10.1016/0031-9422(82)83069-0

Cited by 15 publications

(5 citation statements)

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“…The metabolism of cycloartenol to lanosterol and other sterols by selected species of the Peronosporales indicates that the sterol synthetic pathway past the 2,3-oxidosqualene cyclase (10) showed that cycloartenol, but not lanosterol, produced fucosterol and cholesterol. Conversely, Z. insidians produces ergosterol along with trace amounts oflanosterol and 24-methyl sterols (20). We suggest that Lagenidium and Zoophagus possess differentially enhanced branches of the same overall cycloartenol-derived pathway observed in this study and that these branches function at a more equal level of efficiency in the Peronosporales.…”

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confidence: 49%

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Warner¹,

Eierman²,

Sovocool³

et al. 1982

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

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Selected species of the order Peronosporales, which are unable to epoxidize squalene and thus synthesize sterols, are able to metabolize exogenous cycloartenol to lanosterol and in some organisms to fucosterol, ergosterol, and cholesterol. Lanosterol was less effectively utilized but some ergosterol and cholesterol were yielded. Fucosterol was very efficiently metabolized by most species to ergosterol, A7-ergostenol, A5-ergostenol, cholestanol, and cholesterol. Several unknown sterols were observed in most trials. These data suggest a vestigial sterol synthetic pathway derived from cycloartenol, followed by possible isomerization to lanosterol and then to other sterols.It has been established that species of Pythium and Phytophthora require exogenous sterols for sexual reproduction (1, 2). These organisms are unable to synthesize sterols because of a missing squalene epoxidase (3). Metabolism of exogenous sterols has been observed in Phytophthora cactorum by Langeake (4), who reported possible conversion of lanosterol to cholesterol. Nes and Patterson (5) reported that Phyt. cactorum was unable to transform cycloartenol or lanosterol to other sterols. Conversion ofA7 and A5'7 sterols to A5 sterols has been reported by Elliott and Knights (6) in Phyt. cactorum, which additionally synthesizes cholesteryl esters, cholesteryl glucosides, and acyl sterol glycosides (7,8). Other than the above, sterol conversions in Phytophthora or Pythium have, in general, not been demonstrated in detail.Lagenidium giganteum is another Oomycete, but of the Lagenidiales, that requires exogenous sterols to produce zoospores (9). Warner and Domnas (10) have shown that this organism converts cycloartenol, but not lanosterol, to cholesterol. Because Lagenidium species are able to metabolize cycloartenol, it was ofconsiderable interest to observe ifthis compound could be metabolized by selected species ofthe Peronosporales. This article reports our observations. Inoculation and growth were as described (10) (10) and the unsaponifiable lipid fraction was obtained. The sterols were separated on HPLC with a Waters instrument by using a 10-,um C18 column (4.6 x 250 mm). Fractions were eluted with methanol/H20 (96:4) at 2 ml/min flow with UV detection at 210 nm. MATERIALS AND METHODS MicroorganismsSterols were identified by gas/liquid chromatography on 3% SE-30 and 1% QF-1 with a Packard 417 FID chromatograph as described (10). Confirmation ofidentification was obtained with gas chromatography/electron impact mass spectroscopy (70 eV) with a Finnegan 4023 instrument. A 15-m flexible fused silica capillary coated with OV-101 was programmed from 160 to 2600C at 10°C/min with an initial hold of 3 min. RESULTSNo sterols were found in control organisms to the limit of detection (0.0001%). Uninoculated control cultures yielded a stoichiometric recovery of the administered sterols.Sterols Isolated After Administration ofCycloartenol. Table 1 illustrates the substances identified in the organisms examined. Clear evidence was obtained for the ...

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confidence: 49%

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Warner¹,

Eierman²,

Sovocool³

et al. 1982

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

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“…In addition to molecular analyses, septal pore structure was used as early evidence to suggest a relationship among DHK clade members [14] – [16] . Only two species of the Zoopagales ( Syncephalis spherica and Zoophagus insidians ) have been investigated, and both are reported to have ergosterol as their major sterol [7] , [17] ( Figure 2 ; Table S1 ). It is interesting that Z. insidians was reported to be a pythiaceous oomycete, and the presence of ergosterol supports the placement of this species as a fungus rather than an oomycete.…”

Section: Resultsmentioning

confidence: 99%

Phylogenetic Distribution of Fungal Sterols

Weete¹,

2010

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BackgroundErgosterol has been considered the “fungal sterol” for almost 125 years; however, additional sterol data superimposed on a recent molecular phylogeny of kingdom Fungi reveals a different and more complex situation.Methodology/Principal FindingsThe interpretation of sterol distribution data in a modern phylogenetic context indicates that there is a clear trend from cholesterol and other Δ5 sterols in the earliest diverging fungal species to ergosterol in later diverging fungi. There are, however, deviations from this pattern in certain clades. Sterols of the diverse zoosporic and zygosporic forms exhibit structural diversity with cholesterol and 24-ethyl -Δ5 sterols in zoosporic taxa, and 24-methyl sterols in zygosporic fungi. For example, each of the three monophyletic lineages of zygosporic fungi has distinctive major sterols, ergosterol in Mucorales, 22-dihydroergosterol in Dimargaritales, Harpellales, and Kickxellales (DHK clade), and 24-methyl cholesterol in Entomophthorales. Other departures from ergosterol as the dominant sterol include: 24-ethyl cholesterol in Glomeromycota, 24-ethyl cholest-7-enol and 24-ethyl-cholesta-7,24(28)-dienol in rust fungi, brassicasterol in Taphrinales and hypogeous pezizalean species, and cholesterol in Pneumocystis.Conclusions/SignificanceFive dominant end products of sterol biosynthesis (cholesterol, ergosterol, 24-methyl cholesterol, 24-ethyl cholesterol, brassicasterol), and intermediates in the formation of 24-ethyl cholesterol, are major sterols in 175 species of Fungi. Although most fungi in the most speciose clades have ergosterol as a major sterol, sterols are more varied than currently understood, and their distribution supports certain clades of Fungi in current fungal phylogenies. In addition to the intellectual importance of understanding evolution of sterol synthesis in fungi, there is practical importance because certain antifungal drugs (e.g., azoles) target reactions in the synthesis of ergosterol. These findings also invalidate use of ergosterol as an indicator of biomass of certain fungal taxa (e.g., Glomeromycota). Data from this study are available from the Assembling the Fungal Tree of Life (AFTOL) Structural and Biochemical Database: http://aftol.umn.edu.

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“…Secondly, lanosterol has been isolated without the accompaniment of cycloartenol (albeit, see Sterol Biosynthesis and Metabolism Section). Thirdly, some investigators have found ergosterol in numerous Oomycetes (12,13,21), although this observation has not been confirmed by others in which the same fungus, precursor material, eg. cycloartenol and lanosterol fed to Phytophthora and Lagenidum.…”

Section: Sterol Occurrencementioning

confidence: 94%

“…the ergosterol-producing Ascornycetes; some members failed to synthesize detectable levels of sterols; and the predominant end products characterized by GC-MS, included both 24-desalkyl and 24-alkylidene sterols. In the intervening 15 years additional Oomycetes have been examined for their sterol content (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Table I), and in select fungi the sterol identification has been confirmed by proton magnetic resonance (PMR) spectroscopy (4,11).…”

Section: Sterol Occurrencementioning

confidence: 99%

Biosynthesis and Requirement for Sterols in the Growth and Reproduction of Oomycetes

Nes

1987

ACS Symposium Series

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All Oomycetes fungi possess an obligatory requirement for sterols to complete the sexual stage of their life cycle. Growth is mediated by sterol and in the non-sterol synthesizing Oomycetes additionally by "sterol-like" pen tacyclic and tetracyclic triterpenoids. The structural features and levels which are determinant for bioregulator activity differ amongst the fungi. Herein the bio synthesis and sterol function(s) which operate to control growth are examined and compared with the involvement of sterol in reproduction.

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Ergosterol, the unusual dominant sterol of the pythiaceous fungus Zoophagus insidians

Cited by 15 publications

References 16 publications

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Cycloartenol-derived sterol biosynthesis in the Peronosporales

Phylogenetic Distribution of Fungal Sterols

Biosynthesis and Requirement for Sterols in the Growth and Reproduction of Oomycetes

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