Sterol 24-C-methyltransferase: An enzymatic target for the disruption of ergosterol biosynthesis and homeostasis in Cryptococcus neoformans

W. David Nes, Wenxu Zhou, Kulothungan Ganapathy, Jia Lin Liu, Rit Vatsyayan, Swetha Chamala, Keven Hernandez, Mayra Miranda

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42 Scopus citations

Abstract

Growth of Cryptococcus neoformans was inhibited by nine nitrogen and sulfur-containing sterols with a heteroatom positioned at C3, C7, C24, C25 or C32 in the lanostane frame. Analysis of the sterol composition of control and treated cells by GC-MS and 1H NMR has proven that the C-methylation reaction catalyzed by the sterol 24-C-methyltransferase (24-SMT) is the crucial first step in a kinetically favored pathway that fails to include obtusifoliol or zymosterol as intermediates. Cultures fed [methyl-2H3]methionine led to two deuterium atoms into each of the newly biosynthesized sterols forming a route lanosterol, eburicol (24(28)-methylene-24,25-dihydrolanosterol), 32-noreburicol and ergost-7-enol to ergosterol. Examination of the substrate specificity of a soluble 24-SMT from C. neoformans showed lanosterol to be the optimal acceptor molecule. Incubation with the test compounds generated induced amounts of lanosterol, eburicol or 32-noreburicol concurrent with a decrease of ergosterol. Among them 24(R,S),25-epiminolanosterol (inhibitor of 24-SMT) showed the most potent in vitro antifungal activity comparable to those of itraconazole (inhibitor of the 14-demethylase). Taken together, these data indicate that treatment with substrate-based inhibitors of 24-SMT, a catalyst not found in humans, can disrupt ergosterol homeostasis involved with fungal growth and therefore these compounds can provide leads for rational drug design of opportunistic pathogens.

Original languageEnglish (US)
Pages (from-to)210-218
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume481
Issue number2
DOIs
StatePublished - Jan 15 2009

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Keywords

  • Amphotericin B
  • Antifungal agent
  • Ergosterol
  • Ergosterol biosynthesis inhibitor
  • Itraconazole
  • Lanosterol
  • Membrane
  • Sterol methyl transferase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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