Related Experiment Videos
The mode of action of hirsutellin A on eukaryotic cells
J C Liu1, D G Boucias, J C Pendland
1Department of Entomology and Nematology, University of Florida, Gainesville 32611, USA.
Abstract:
A 16-kDa protein toxin was purified from Hirsutella thompsonii var thompsonii and named hirsutellin A (HtA). At 0.5 and 5.0 microM concentrations, HtA caused detectable cytopathic effects on Spodoptera frugiperda cells (Sf-9) within 2-4 hr and completely inhibited Sf-9 cell growth at 4 days posttreatment. Electron microscope data showed that the HtA treated Sf-9 cells became hypotrophied and internal organelles and cell membranes were disrupted. At the same concentration, HtA effectively inhibited Brome mosaic virus protein synthesis of both rabbit reticulocyte and wheat germ in vitro translation system. The ribosomal RNA extracted from HtA treated Sf-9 cells produced a smaller RNA (approximately 528 bases) than untreated Sf-9 cells. In summary, HtA is the first mycotoxin of a invertebrate mycopathogen determined to possess ribosomal inhibiting activity and appears to possess some specificity to invertebrate cells.
Insights
Hirsutellin A (HtA), a novel protein toxin from Hirsutella thompsonii, inhibits invertebrate cell growth and protein synthesis by targeting ribosomes. This mycotoxin shows specificity towards invertebrate cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Mycology
Background:
- Hirsutella thompsonii var thompsonii is an entomopathogenic fungus.
- Protein toxins produced by entomopathogens can have significant biological activity.
Purpose of the Study:
- To purify and characterize a novel protein toxin from Hirsutella thompsonii var thompsonii.
- To investigate the biological activity and mechanism of action of this toxin on invertebrate cells and viral protein synthesis.
Main Methods:
- Purification of a 16-kDa protein toxin, named hirsutellin A (HtA).
- Assessment of cytopathic effects and cell growth inhibition on Spodoptera frugiperda (Sf-9) cells.
- Electron microscopy to observe cellular damage.
- In vitro inhibition assays using rabbit reticulocyte and wheat germ translation systems.
- Analysis of ribosomal RNA from treated and untreated cells.
Main Results:
- HtA induced cytopathic effects and completely inhibited Sf-9 cell growth at 0.5 and 5.0 microM concentrations.
- Electron microscopy revealed cell hypotrophy and disruption of organelles and membranes in HtA-treated cells.
- HtA inhibited Brome mosaic virus protein synthesis in vitro and altered ribosomal RNA structure in Sf-9 cells.
Conclusions:
- HtA is the first identified mycotoxin from an invertebrate mycopathogen with ribosomal inhibiting activity.
- HtA exhibits specificity towards invertebrate cells, suggesting potential applications in pest control or as a research tool.