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

EMBO J. 2001 Aug 1;20(15):4309-23. doi: 10.1093/emboj/20.15.4309.

Abstract

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:

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Base Sequence
  • Chromosome Mapping
  • Cloning, Molecular
  • Cytosine / metabolism*
  • DNA (Cytosine-5-)-Methyltransferases / genetics*
  • DNA (Cytosine-5-)-Methyltransferases / metabolism
  • DNA (Cytosine-5-)-Methyltransferases / physiology
  • DNA Helicases / metabolism
  • DNA Methylation*
  • DNA, Fungal
  • DNA-Binding Proteins*
  • Genes, Fungal
  • Genetic Complementation Test
  • Genetic Variation
  • Molecular Sequence Data
  • Neurospora crassa / enzymology*
  • Neurospora crassa / genetics
  • Sequence Homology, Amino Acid
  • Trans-Activators / metabolism

Substances

  • DNA, Fungal
  • DNA-Binding Proteins
  • Trans-Activators
  • replication initiator protein
  • Cytosine
  • DNA (Cytosine-5-)-Methyltransferases
  • DNA Helicases

Associated data

  • GENBANK/AF348971