title: Methylation of glycosylated sphingolipid modulates membrane lipid topography and pathogenicity of Cryptococcus neoformans.
abstract: In previous studies we showed that the replication of Cryptococcus neoformans in the lung environment is controlled by the glucosylceramide (GlcCer) synthase gene (GCS1), which synthesizes the membrane sphingolipid GlcCer from the C9-methyl ceramide. Here, we studied the effect of the mutation of the sphingolipid C9 methyltransferase gene (SMT1), which adds a methyl group to position 9 of the sphingosine backbone of ceramide. The C. neoformans Δsmt1 mutant does not make C9-methyl ceramide and, thus, any methylated GlcCer. However, it accumulates demethylated ceramide and demethylated GlcCer. The Δsmt1 mutant loses more than 80% of its virulence compared with the wild type and the reconstituted strain. Interestingly, growth of C. neoformans Δsmt1 in the lung was decreased and C. neoformans cells were contained in lung granulomas, which significantly reduced the rate of their dissemination to the brain reducing the onset of meningoencephalitis. Thus, using fluorescent spectroscopy and atomic force microscopy we compared the wild type and Δsmt1 mutant and found that the altered membrane composition and GlcCer structure affects fungal membrane rigidity, suggesting that specific sphingolipid structures are required for proper fungal membrane organization and integrity. Therefore, we propose that the physical structure of the plasma membrane imparted by specific classes of sphingolipids represents a critical factor for the ability of the fungus to establish virulence.
authors.affiliation: Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA.
authors.forename: Arpita
authors.initials: A
authors.lastname: Singh
authors.forename: Haitao
authors.initials: H
authors.lastname: Wang
authors.forename: Liana C
authors.initials: LC
authors.lastname: Silva
authors.forename: Chongzheng
authors.initials: C
authors.lastname: Na
authors.forename: Manuel
authors.initials: M
authors.lastname: Prieto
authors.forename: Anthony H
authors.initials: AH
authors.lastname: Futerman
authors.forename: Chiara
authors.initials: C
authors.lastname: Luberto
authors.forename: Maurizio
authors.initials: M
authors.lastname: Del Poeta
mesh_terms: D000818:Animals; D001921:Brain / Q000382:microbiology / Q000473:pathology; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002494:Central Nervous System Infections / Q000382:microbiology; D003453:Cryptococcosis / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005963:Glucosylceramides / Q000235:genetics / Q000378:metabolism*; D006099:Granuloma / Q000382:microbiology / Q000473:pathology; D054884:Host-Pathogen Interactions; D006863:Hydrogen-Ion Concentration; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008563:Membrane Lipids / Q000235:genetics / Q000378:metabolism*; D008590:Meningoencephalitis / Q000382:microbiology / Q000473:pathology; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008808:Mice, Inbred CBA; D018625:Microscopy, Atomic Force; D009154:Mutation; D013050:Spectrometry, Fluorescence; D013107:Sphingolipids / Q000235:genetics / Q000378:metabolism*; D013110:Sphingosine / Q000235:genetics / Q000378:metabolism; D014774:Virulence
chemical_list: D005963:Glucosylceramides; D008563:Membrane Lipids; D013107:Sphingolipids; D008780:Methyltransferases; D013110:Sphingosine