Glycosylphosphatidylinositols synthesized by Trichophyton rubrum in a cell-free system
Ulrike Pusch1, Isaak Effendy, Ralph T Schwarz
1Institut für Virology, Medizinisches Zentrum für Hygiene und Medizinische Mikrobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 17, D-35037 Marburg, Germany.
Abstract:
The opportunistic fungi Trichophyton rubrum and T. mentagrophytes, are responsible for relatively non-inflammatory chronic dermatophytes infections in immunocompromised patients but also in healthy individuals. This chronic infection is associated with immunosuppressive effects of the cell wall components particularly the polysaccharides secreted by these organisms. We have studied glycosylphosphatidylinositol (GPI) anchor biosynthesis in the pathogenic fungus T. rubrum and could demonstrate that T. rubrum is able to synthesize GPI structures. Glycolipids synthesized in a cell-free system prepared from the dermatophyte T. rubrum and labeled with [3H]mannose, and [3H]galactose using GDP-[3H]mannose and UDP-[3H]galactose, respectively, were identified and structurally characterized as GPIs. The evolutionary conserved backbone of T. rubrum GPIs incorporates galactose. Further, all glycolipids lack the acyl group on the inositol which was shown for Saccharomyces cerevisiae and mammalian GPIs. Our data suggest significant differences in the GPI biosynthetic pathway between mammalian and T. rubrum cells that could perhaps be exploited for the development of an antimycotic for Trichophyton infection.
Insights
Trichophyton rubrum synthesizes unique glycosylphosphatidylinositol (GPI) structures, differing from mammalian GPIs. These differences in GPI biosynthesis may offer new targets for antifungal treatments against Trichophyton infections.
Area of Science:
- Mycology
- Biochemistry
- Medical Mycology
Background:
- Opportunistic fungi, Trichophyton rubrum and T. mentagrophytes, cause chronic dermatophytosis.
- Fungal cell wall polysaccharides, particularly secreted ones, contribute to immunosuppressive effects.
- Glycosylphosphatidylinositol (GPI) anchors are crucial cell surface components in eukaryotes.
Purpose of the Study:
- To investigate glycosylphosphatidylinositol (GPI) anchor biosynthesis in the pathogenic fungus Trichophyton rubrum.
- To characterize the structure of GPIs synthesized by T. rubrum.
- To identify potential differences in GPI biosynthesis between T. rubrum and mammalian cells for therapeutic exploitation.
Main Methods:
- Utilized a cell-free system derived from T. rubrum.
- Incorporated radiolabeled precursors: [3H]mannose and [3H]galactose.
- Identified and structurally characterized synthesized glycolipids as GPIs using biochemical and analytical techniques.
Main Results:
- Demonstrated that T. rubrum can synthesize GPI structures.
- Identified T. rubrum GPIs containing a conserved backbone with incorporated galactose.
- Observed a lack of inositol acylation in T. rubrum GPIs, distinguishing them from Saccharomyces cerevisiae and mammalian GPIs.
Conclusions:
- Significant differences exist in the GPI biosynthetic pathway between T. rubrum and mammalian cells.
- The unique GPI structure of T. rubrum presents a potential target for novel antifungal drug development.
- Exploiting these pathway differences could lead to effective antimycotic therapies for Trichophyton infections.
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