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Molecular action of tricholin, a ribosome-inactivating protein isolated from Trichoderma viride
1Institute of Genetics, National Yang-Ming Medical College, Taipei, Taiwan, Republic of China.
Abstract:
An extracellular protein was isolated from a species of soil-borne fungi (Trichoderma viride) and its amino acid composition has been determined. The protein is acidic with a molecular mass of 14,200 daltons and is given the trivial name tricholin. Tricholin is a potent inhibitor of cell-free protein synthesis. When rabbit reticulocyte lysate was incubated with tricholin at a concentration of 6.3 x 10(-7) M, it completely abolished the capacity of the lysate to support protein synthesis. The inhibition appears to be due to its reaction to ribosomes, since it generates a specific cleavage product, an alpha-sarcin RNA fragment, from reticulocyte ribosomal RNA. This reaction to ribosomes mimics that of alpha-sarcin. The antibody of alpha-sarcin strongly cross-reacts with tricholin, while the antibody of tricholin shows a weak reaction with alpha-sarcin.
Insights
A novel fungal protein, tricholin, inhibits protein synthesis by targeting ribosomes. This protein, isolated from Trichoderma viride, mimics alpha-sarcin activity by cleaving ribosomal RNA.
Area of Science:
- Biochemistry
- Molecular Biology
- Mycology
Background:
- Soil-borne fungi like Trichoderma viride produce various bioactive compounds.
- Protein synthesis is a fundamental cellular process regulated by numerous factors.
- Ribosomes are the cellular machinery responsible for protein synthesis.
Purpose of the Study:
- To isolate and characterize an extracellular protein from Trichoderma viride.
- To investigate the inhibitory effects of the isolated protein on cell-free protein synthesis.
- To elucidate the mechanism of action of the protein, particularly its interaction with ribosomes.
Main Methods:
- Isolation and purification of an extracellular protein from Trichoderma viride.
- Determination of the protein's amino acid composition and molecular mass.
- Assay of the protein's effect on rabbit reticulocyte lysate protein synthesis.
- Analysis of ribosomal RNA cleavage products and cross-reactivity with alpha-sarcin antibodies.
Main Results:
- An acidic extracellular protein, named tricholin, with a molecular mass of 14,200 daltons was isolated.
- Tricholin potently inhibited cell-free protein synthesis in rabbit reticulocyte lysate at 6.3 x 10(-7) M.
- Tricholin induced cleavage of ribosomal RNA, generating an alpha-sarcin RNA fragment, indicating ribosome interaction.
- Antibodies against alpha-sarcin showed strong cross-reactivity with tricholin, and vice versa.
Conclusions:
- Tricholin is a novel, potent inhibitor of protein synthesis originating from Trichoderma viride.
- The mechanism of inhibition involves direct interaction with ribosomes, leading to ribosomal RNA cleavage.
- Tricholin's activity and immunological cross-reactivity suggest functional and structural similarities to alpha-sarcin.