Masc2, a gene from Ascobolus encoding a protein with a DNA‐methyltransferase activity in vitro, is dispensable for in vivo methylation

Malagnac, Fabienne; Grégoire, Annie; Goyon, Christophe; Rossignol, Jean‐Luc; Faugeron, Godeleine

doi:10.1046/j.1365-2958.1999.01177.x

Cited by 25 publications

(19 citation statements)

References 30 publications

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“…AF007807), suggests that Masc2 is not a true ortholog of dim‐2 . Consistent with this hypothesis is the observation that disruption of Masc2 does not affect methylation in Ascobolus (Malagnac et al ., 1999).…”

Section: Discussionmentioning

confidence: 99%

dim-2 encodes a DNA methyltransferase responsible for all known cytosine methylation in Neurospora

2001

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To understand better the control of DNA methylation, we cloned and characterized the dim-2 gene of Neurospora crassa, the only eukaryotic gene currently known in which mutations appear to eliminate DNA methylation. The dim-2 gene is responsible for methylation in both symmetrical and asymmetrical sites. We mapped dim-2 between wc-1 and un-10 on linkage group (LG) VIIR and identi®ed the gene by RFLP mapping and genetic complementation. Dim-2 encodes a 1454 amino acid protein including a C-terminal domain homologous to known DNA methyltransferases (MTases) and a novel N-terminal domain. Neither a deletion that removed the ®rst 186 amino acids of the protein nor a mutation in a putative nucleotide binding site abolished function, but a single amino acid substitution in the predicted catalytic site did. Tests for repeat-induced point mutation (RIP) indicated that dim-2 does not play a role in this process, i.e. duplicated sequences are mutated in dim-2 strains, as usual, but the mutated sequences are not methylated, unlike the situation in dim-2 + strains. We conclude that dim-2 encodes an MTase that is responsible for all DNA methylation in vegetative tissues of Neurospora.

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Section: Discussionmentioning

confidence: 99%

dim-2 encodes a DNA methyltransferase responsible for all known cytosine methylation in Neurospora

2001

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“…This enzyme is catalytically active in vitro, but a knock-out did not reveal any phenotype in vivo. [263,264] Therefore, an additional DNA MTase responsible for maintenance methylation must be present in A. immersus.…”

Section: Dna Mtases In Fungimentioning

confidence: 99%

Beyond Watson and Crick: DNA Methylation and Molecular Enzymology of DNA Methyltransferases

2002

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DNA methyltransferases catalyze the transfer of a methyl group from S-adenosyl-L-methionine to cytosine or adenine bases in DNA. These enzymes challenge the Watson/Crick dogma in two instances: 1) They attach inheritable information to the DNA that is not encoded in the nucleotide sequence. This so-called epigenetic information has many important biological functions. In prokaryotes, DNA methylation is used to coordinate DNA replication and the cell cycle, to direct postreplicative mismatch repair, and to distinguish self and nonself DNA. In eukaryotes, DNA methylation contributes to the control of gene expression, the protection of the genome against selfish DNA, maintenance of genome integrity, parental imprinting, X-chromosome inactivation in mammals, and regulation of development. 2) The enzymatic mechanism of DNA methyltransferases is unusual, because these enzymes flip their target base out of the DNA helix and, thereby, locally disrupt the B-DNA helix. This review describes the biological functions of DNA methylation in bacteria, fungi, plants, and mammals. In addition, the structures and mechanisms of the DNA methyltransferases, which enable them to specifically recognize their DNA targets and to induce such large conformational changes of the DNA, are discussed.

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“…During RIP and MIP, the methylation occurs at cytosine residues in a variety of sequences and is not mainly found at CpG or CpNpG sequences as it is for animals and vascular plants. A. immersus contains two active DNA methyltransferases, Masc1 which is involved in MIP [13], and Masc2 whose biological function is not known [14,15]. In N. crassa only one Mtase, Dim‐2, has been identified [16].…”

Section: Introductionmentioning

confidence: 99%

DNA fromAspergillus flavuscontains 5-methylcytosine

Gowher¹,

Ehrlich

Jeltsch³

2001

FEMS Microbiology Letters

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DNA from Aspergillus sp. has been reported not to contain 5-methylcytosine. However, it has been found that Aspergillus nidulans responds to 5-azacytidine, a drug that is a strong inhibitor of DNA methyltransferases. Therefore, we have re-examined the occurrence of 5-methylcytosine in DNA from Aspergillus flavus by using a highly sensitive and specific method for detection of modified bases in genomic DNA comprising high-performance liquid chromatography separation of nucleosides, labeling of the nucleoside with deoxynucleoside kinase and two-dimensional thin-layer chromatography. Our results show that 5-methylcytosine is present in DNA from A. flavus. We estimate the relative amounts of 5-methylcytosine to cytosine to be approximately 1/400.

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Masc2, a gene from Ascobolus encoding a protein with a DNA‐methyltransferase activity in vitro, is dispensable for in vivo methylation

Cited by 25 publications

References 30 publications

dim-2 encodes a DNA methyltransferase responsible for all known cytosine methylation in Neurospora

dim-2 encodes a DNA methyltransferase responsible for all known cytosine methylation in Neurospora

Beyond Watson and Crick: DNA Methylation and Molecular Enzymology of DNA Methyltransferases

DNA fromAspergillus flavuscontains 5-methylcytosine

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