Open AccessDirect Interaction between DNA Methyltransferase DIM-2 and HP1 Is Required for DNA Methylation in Neurospora crassa
Author(s) -
Shinji Honda,
Eric U. Selker
Publication year - 2008
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00823-08
Subject(s) - heterochromatin protein 1 , biology , histone methyltransferase , histone methylation , neurospora crassa , heterochromatin , dna methylation , methylation , methyltransferase , histone , genetics , microbiology and biotechnology , dna methyltransferase , dna , chromatin , gene , gene expression , mutant
DNA methylation is involved in gene silencing and genomic stability in mammals, plants, and fungi. Genetics studies ofNeurospora crassa have revealed that a DNA methyltransferase (DIM-2), a histone H3K9 methyltransferase (DIM-5), and heterochromatin protein 1 (HP1) are required for DNA methylation. We explored the interrelationships of these components of the methylation machinery. A yeast two-hybrid screen revealed that HP1 interacts with DIM-2. We confirmed the interaction in vivo and demonstrated that it involves a pair of PXVXL-related motifs in the N-terminal region of DIM-2 and the chromo shadow domain of HP1. Both regions are essential for proper DNA methylation. We also determined that DIM-2 and HP1 form a stable complex independently of the trimethylation of histone H3K9, although the association of DIM-2 with its substrate sequences depends on trimethyl-H3K9. The DIM-2/HP1 complex does not include DIM-5. We conclude that DNA methylation inNeurospora is largely or exclusively the result of a unidirectional pathway in which DIM-5 methylates histone H3K9 and then the DIM-2/HP1 complex recognizes the resulting trimethyl-H3K9 mark via the chromo domain of HP1.