Identification of fungal sphingolipid C9-methyltransferases by phylogenetic profiling.
J Biol Chem
; 281(9): 5582-92, 2006 Mar 03.
Article
em En
| MEDLINE
| ID: mdl-16339149
ABSTRACT
Fungal glucosylceramides play an important role in plant-pathogen interactions enabling plants to recognize the fungal attack and initiate specific defense responses. A prime structural feature distinguishing fungal glucosylceramides from those of plants and animals is a methyl group at the C9-position of the sphingoid base, the biosynthesis of which has never been investigated. Using information on the presence or absence of C9-methylated glucosylceramides in different fungal species, we developed a bioinformatics strategy to identify the gene responsible for the biosynthesis of this C9-methyl group. This phylogenetic profiling allowed the selection of a single candidate out of 24-71 methyltransferase sequences present in each of the fungal species with C9-methylated glucosylceramides. A Pichia pastoris knock-out strain lacking the candidate sphingolipid C9-methyltransferase was generated, and indeed, this strain contained only non-methylated glucosylceramides. In a complementary approach, a Saccharomyces cerevisiae strain was engineered to produce glucosylceramides suitable as a substrate for C9-methylation. C9-methylated sphingolipids were detected in this strain expressing the candidate from P. pastoris, demonstrating its function as a sphingolipid C9-methyltransferase. The enzyme belongs to the superfamily of S-adenosylmethionine-(SAM)-dependent methyltransferases and shows highest sequence similarity to plant and bacterial cyclopropane fatty acid synthases. An in vitro assay showed that sphingolipid C9-methylation is membrane-bound and requires SAM and Delta4,8-desaturated ceramide as substrates.
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Base de dados:
MEDLINE
Assunto principal:
Esfingolipídeos
/
Proteínas Fúngicas
/
Glucosilceramidas
/
Metiltransferases
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2006
Tipo de documento:
Article