dim-2 encodes a DNA methyltransferase responsible for all known cytosine methylation in Neurospora.
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 identified 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 first 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:
Kouzminova
E
E
Department of Biology and Institute of Molecular Biology, University of Oregon, Eugene, Oregon, OR 97403-1229, USA.
Selker
E U
EU
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003596:Cytosine / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D004265:DNA Helicases / Q000378:metabolism; D019175:DNA Methylation; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D003596:Cytosine; D004248:DNA (Cytosine-5-)-Methyltransferases; D004265:DNA Helicases