Abstract
The protein encoded by the second intron (bi2) of the mitochondrial cyt b gene from Saccharomyces cerevisiae functions as a maturase promoting intron splicing. This protein belongs to a large family characterized by the presence of two conserved motifs: LAGLIDADG (or P1 and P2). We have isolated and characterized spontaneous revertants from two mis-sense mutations, G85D and H92P (localized in the P1 motif of the bi2-maturase), that have a detrimental effect on intron splicing. All analyzed revertants are intragenic and resulted from monosubstitutions in the mutated codons. Only true back-mutations that restore the initial glycine 85 and a pseudoreversion that replaces the deleterious aspartic acid 85 by alanine were found in revertants of the mutant G85D. In contrast, all possible monosubstitutions in the mutated codon H92P were identified among the revertants of this mutant. The maturase activity of all novel forms of the protein is similar to the wild-type protein.
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Acknowledgements
We thank Christopher J. Herbert for critical reading of the manuscript and correcting the English and thank D. Menay for the synthesis of oligonucleotides. E.M. was the recipient of a doctoral fellowship from the CNRS within the framework of the Centre Franco–Polonais de Biotechnologie des Plantes.
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Maciaszczyk, E., Ulaszewski, S. & Lazowska, J. Intragenic suppressors that restore the activity of the maturase encoded by the second intron of the Saccharomyces cerevisiae cyt b gene. Curr Genet 46, 67–71 (2004). https://doi.org/10.1007/s00294-004-0509-5
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DOI: https://doi.org/10.1007/s00294-004-0509-5