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Masc2, a gene from Ascobolus encoding a protein with a DNA-methyltransferase activity in vitro, is dispensable for in
F Malagnac1, A Grégoire, C Goyon
1Institut Jacques Monod, Département de Microbiologie, UMR 7592: CNRS/Université Paris 7/Université Paris 6, France.
Abstract:
We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
Insights
The masc2 gene in Ascobolus is not responsible for DNA methylation maintenance or de novo methylation. Further research is needed to identify the gene responsible for these essential methylation processes.
Area of Science:
- Genetics
- Molecular Biology
- Epigenetics
Background:
- DNA methylation is crucial for gene regulation and reproduction.
- The masc1 gene is essential for de novo methylation and sexual reproduction in Ascobolus.
- The masc2 gene encodes a putative DNA methyltransferase.
Purpose of the Study:
- To investigate the in vivo function of the masc2 gene in Ascobolus.
- To determine if masc2 is responsible for maintenance methylation.
- To assess the role of masc2 in de novo methylation and sexual reproduction.
Main Methods:
- Gene disruption of masc2 in Ascobolus.
- Phenotypic analysis of masc2 mutant strains during vegetative growth and sexual reproduction.
- Analysis of DNA methylation patterns in masc2 mutants.
Main Results:
- Masc2 disruption did not affect vegetative growth or sexual reproduction.
- The masc2 mutation had no detectable effect on the maintenance of pre-existing methylation.
- Masc2 mutation did not alter de novo methylation processes or meiotic methylation transfer.
Conclusions:
- Masc2 is not the primary DNA methyltransferase responsible for maintenance methylation in Ascobolus.
- Ascobolus likely possesses at least one additional DNA methyltransferase gene for maintenance and vegetative de novo methylation.
- Further investigation is required to identify the complete set of DNA methyltransferases in Ascobolus.