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

Nes, W. David

doi:10.1021/bk-1987-0325.ch019

Cited by 43 publications

(21 citation statements)

References 30 publications

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“…Mycelium from a 10-day-old culture of P. iultimum grown under these conditions contained 8.9 ,ug of total sterol. The sterol composition of the fungus approximated that found in V8 juice, i.e., relatively high amounts of sitosterol and stigmasterol and smaller quantities of campesterol and cholesterol (47). An ethereal extract of V8 juice used in these experiments revealed the following sterol composition: 50.5% sitosterol, 34.2% stigmasterol, 13.7% campesterol, and 1.6% cholesterol.…”

Section: Resultssupporting

confidence: 51%

“…Highly purified soybean lecithin has been shown to contain detectable levels of sterols (47). Two separate lots of synthetic dioleoyl phosphatidylcholine ( "The basal growth medium was the defined medium described by Ko (37).…”

Section: Resultsmentioning

confidence: 99%

“…Sterols have a well-documented ability to modulate membrane fluidity (2, 3, 10, 52), which affects permeability (25,40,43) and protein mobility and enzymic activity (35,36,51). In addition to this bulk role of sterols, studies on mycoplasmas (7,8), the yeast Saccharomyces cereiisiae (54,55), P. cactorlln (47), and L. gigantelum (unpublished observations) have implicated a second, more specific sparking effect of these compounds on growth and reproduction. A recent study of S. cerevisiae has implicated four separate levels of physiological function for sterols in supporting the growth of this yeast (53).…”

Section: Resultsmentioning

confidence: 99%

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Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Kerwin

Duddles

1989

J Bacteriol

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Several genera of oomycete fungi which are incapable of de novo sterol synthesis do not require these compounds for vegetative growth. The requirement for an exogenous source of sterols for sexual reproduction by several members of the Pythiaceae has been questioned by reports of apparent induction and maturation of oospores on defined media supplemented with phospholipids in the absence of sterols. A more detailed examination of this phenomenon suggested that trace levels of sterols in the inoculum of some pythiaceous fungi act synergistically with phospholipid medium supplements containing unsaturated fatty acid moieties to induce oosporogenesis. Phospholipid analysis of one species, Pythium ultimum, suggested that only the fatty acid portion of the exogenous phospholipid is taken up by the fungus. Enrichment of the phospholipid fraction of total cell lipid of P. ultimum with unsaturated fatty acids promoted oospore induction, and enhanced levels of unsaturated fatty acids in the neutral lipid fraction increased oospore viability. For some pythiaceous fungi, the levels of sterols required for the maturation of oospores with appropriate phospholipid medium supplementation suggest that these compounds are necessary only for the sparking and critical domain roles previously described in other fungi.

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Section: Resultssupporting

confidence: 51%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Kerwin

Duddles

1989

J Bacteriol

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“…These were shown to be derived from laboratory articles made of natural rubber, such as pipette fillers and latex gloves. Agar can also contain cholesterol and 24-ethylcholesta-5,22E-dien-3b-ol (Nes 1987). Unfortunately, all too few lipid analyses of microorganisms report the results of blank analyses.…”

Section: Occurrence Of Sterols In Other Bacteriamentioning

confidence: 99%

Sterols in microorganisms

Volkman

2003

Appl Microbiol Biotechnol

737

478

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Sterols are vital components of all eukaryotic cells. This review describes the variety of sterol structures found in microalgae, yeasts, fungi, protozoans and microheterotrophs. Reports of the occurrence of sterols in prokaryotic cells are critically assessed. Methylotrophic bacteria contain unusual 4-methylsterols, but reports of 4-desmethyl sterols in cyanobacteria and other bacteria are limited and many of these seem dubious. Possible application areas for sterols derived from mass culture of microalgae and other microorganisms are highlighted.

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“…For aerobic bacteria such as Mycobacterium tuberculosis (MT) (3), the architectural requirements of the cell membrane can be satisfied by either sterol surrogates, e.g., pentacyclic hopanoids (4, 5) synthesized directly from squalene by an anaerobic pathway, or by sterols synthesized from squalene by an aerobic pathway (1). However, based on our knowledge that sterols play a dual role in eukaryotic cell physiology at vastly different cellular concentrations, structurally as bulk inserts to affect permeability and hormonally to regulate growth, reproduction, and other processes (6)(7)(8), the level of cellular sterols in bacteria may be substantially less than even the hormonal level required in eukaryotes. In bacteria (1), sterol concentration was found to be two or more orders of magnitude less than the level in eukaryotic cells, which ranges from ca.…”

mentioning

confidence: 99%

Characterization and catalytic properties of the sterol 14α-demethylase from Mycobacterium tuberculosis

Bellamine

et al. 1999

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

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211

190

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Sterol 14␣-demethylase encoded by CYP51 is a mixed-function oxidase involved in sterol synthesis in eukaryotic organisms. Completion of the Mycobacterium tuberculosis genome project revealed that a protein having homology to mammalian 14␣-demethylases might be present in this bacterium. Using genomic DNA from mycobacterial strain H 37 Rv, we have established unambiguously that the CYP51-like gene encodes a bacterial sterol 14␣-demethylase. Expression of the M. tuberculosis CYP51 gene in Escherichia coli yields a P450, which, when purified to homogeneity, has the predicted molecular mass, ca. 50 kDa on SDS͞PAGE, and binds both sterol substrates and azole inhibitors of P450 14␣-demethylases. It catalyzes 14␣-demethylation of lanosterol, 24,25-dihydrolanosterol, and obtusifoliol to produce the 8,14-dienes stereoselectively as shown by GC͞MS and 1 H NMR analysis. Both f lavodoxin and ferredoxin redox systems are able to support this enzymatic activity. Structural requirements of a 14␣-methyl group and ⌬ 8(9) -bond were established by comparing binding of pairs of sterol substrate that differed in a single molecular feature, e.g., cycloartenol paired with lanosterol. These substrate requirements are similar to those established for plant and animal P450 14␣-demethylases. From the combination of results, the interrelationships of substrate functional groups within the active site show that oxidative portions of the sterol biosynthetic pathway are present in prokaryotes.

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

Cited by 43 publications

References 30 publications

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Sterols in microorganisms

Characterization and catalytic properties of the sterol 14α-demethylase from Mycobacterium tuberculosis

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