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Killer toxin secretion through the cell wall of the yeast Pichia anomala
J C Cailliez1, C Cantelli, N Séguy
1Unité 42, Institut National de la Santé et de la Recherche Médicale, Villeneuve d'Ascq, France.
Abstract:
A secreted killer toxin was detected through the cell wall of Pichia anomala cells by ultrastructural immunodetection with a specific monoclonal antibody (MAb KT4). MAb KT4 was successively detected by colloidal gold labeled streptavidin and biotinylated anti-mouse F(ab')2 antibodies. The antigenic determinants of the toxin were localized throughout the cytoplasm and the cell wall of killer yeast cells. The Lowicryl K4M-immunogold method gave very satisfactory results and showed that the killer toxin was somewhat concentrated in the yeast cell wall layers before being exported into the medium. In agreement with previous reports, the binding of MAb KT4 suggested that the P. anomala killer toxin secretion did not result from a homogeneous diffusion across the yeast cell wall.
Insights
Pichia anomala killer toxin is secreted through the cell wall. Ultrastructural immunodetection revealed the toxin concentrates in cell wall layers before export, not via homogeneous diffusion.
Area of Science:
- * Microbiology
- * Cell Biology
- * Immunology
Background:
- * Pichia anomala is a yeast species known to produce killer toxins.
- * Understanding the secretion mechanism of these toxins is crucial for their application and for yeast cell biology.
- * Previous studies suggested non-homogeneous secretion, but localization details were lacking.
Purpose of the Study:
- * To ultrastructurally localize the secreted killer toxin of Pichia anomala.
- * To investigate the pathway of toxin secretion across the yeast cell wall.
- * To determine if toxin secretion is a homogeneous diffusion process.
Main Methods:
- * Ultrastructural immunodetection using a specific monoclonal antibody (MAb KT4).
- * Detection involved colloidal gold-labeled streptavidin and biotinylated anti-mouse F(ab')2 antibodies.
- * Lowicryl K4M embedding and immunogold labeling for high-resolution imaging.
Main Results:
- * The killer toxin's antigenic determinants were localized in the cytoplasm and cell wall of P. anomala.
- * The toxin was observed to concentrate in the yeast cell wall layers prior to export.
- * Immunogold labeling confirmed toxin presence within the cell wall structure.
Conclusions:
- * The P. anomala killer toxin is secreted via a pathway involving concentration within cell wall layers.
- * Secretion is not a simple homogeneous diffusion process across the cell wall.
- * Ultrastructural immunodetection provides valuable insights into yeast toxin secretion mechanisms.