Related Experiment Videos
maf1 mutation alters the subcellular localization of the Mod5 protein in yeast
M Murawski1, B Szcześniak, T Zoładek
1Department of Genetics, Polish Academy of Sciences, Warsaw.
Abstract:
Two forms of Mod5p, a tRNA modification enzyme, are found in three intracellular compartments, mitochondria, cytoplasm and nucleus, but are encoded by a single MOD5 gene. The two forms of the enzyme, Mod5p-I and Mod5p-II differ at the N-termini and are produced by initiation of translation at different start codons. Mod5p-I does contain a mitochondrial targeting signal and is distributed between mitochondria and cytoplasm, whereas Mod5p-II is found in the cytosol and nucleus (Boguta, M., et al. 1994, Mol. Cell. Biol. 14, 2298-2306). In the present work mutants which mislocalize the Mod5p-I enzyme were isolated. The screen was based on a correlation between the amount of cytosolic protein and the efficiency of tRNA mediated suppression. Identification of mutants is possible because a red pigment accumulates in the cells unable to suppress an ade2-1 nonsense allele. The maf1 mutant, with an altered intracellular localization of the Mod5p-I protein, was isolated. Immunofluorescence data suggest that the mutation causes mislocalization of the Mod5p-I to the nucleus.
Insights
Researchers identified a new mutant, maf1, affecting the Mod5p-I enzyme
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The Mod5p enzyme, crucial for tRNA modification, exists in two forms (Mod5p-I and Mod5p-II).
- These forms are localized to mitochondria, cytoplasm, and nucleus, despite originating from a single MOD5 gene.
- Mod5p-I contains a mitochondrial targeting signal, directing it to mitochondria and cytoplasm, while Mod5p-II resides in the cytosol and nucleus.
Purpose of the Study:
- To isolate and characterize mutants that mislocalize the Mod5p-I enzyme.
- To understand the functional consequences of Mod5p-I mislocalization on tRNA-mediated suppression.
Main Methods:
- A genetic screen was employed, correlating cytosolic Mod5p levels with tRNA suppression efficiency.
- Mutant identification was facilitated by a red pigment accumulation phenotype in cells with impaired suppression of an ade2-1 nonsense allele.
- Immunofluorescence microscopy was used to determine protein localization within the cell.
Main Results:
- A novel mutant, maf1, was identified, exhibiting altered intracellular localization of Mod5p-I.
- Immunofluorescence data indicated that the maf1 mutation causes Mod5p-I to be mislocalized to the nucleus.
- This mislocalization impacts the enzyme's function in tRNA-mediated suppression.
Conclusions:
- The maf1 mutation disrupts the proper localization of Mod5p-I.
- Nuclear mislocalization of Mod5p-I affects tRNA modification and suppression efficiency.
- This study provides insights into the regulatory mechanisms governing Mod5p localization and function.