SRA-domain proteins required for DRM2-mediated de novo DNA methylation.
De novo DNA methylation and the maintenance of DNA methylation in asymmetrical sequence contexts is catalyzed by homologous proteins in plants (DRM2) and animals (DNMT3a/b). In plants, targeting of DRM2 depends on small interfering RNAs (siRNAs), although the molecular details are still unclear. Here, we show that two SRA-domain proteins (SUVH9 and SUVH2) are also essential for DRM2-mediated de novo and maintenance DNA methylation in Arabidopsis thaliana. At some loci, SUVH9 and SUVH2 act redundantly, while at other loci only SUVH2 is required, and this locus specificity correlates with the differing DNA-binding affinity of the SRA domains within SUVH9 and SUVH2. Specifically, SUVH9 preferentially binds methylated asymmetric sites, while SUVH2 preferentially binds methylated CG sites. The suvh9 and suvh2 mutations do not eliminate siRNAs, suggesting a role for SUVH9 and SUVH2 late in the RNA-directed DNA methylation pathway. With these new results, it is clear that SRA-domain proteins are involved in each of the three pathways leading to DNA methylation in Arabidopsis.
Johnson
Lianna M
LM
Life Sciences Core Curriculum, University of California Los Angeles, Los Angeles, California, United States of America.
Law
Julie A
JA
Khattar
Anuj
A
Henderson
Ian R
IR
Jacobsen
Steven E
SE
D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019175:DNA Methylation; D006570:Heterochromatin / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000096:biosynthesis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C416366:FWA protein, Arabidopsis; D006570:Heterochromatin; D006657:Histones; D018398:Homeodomain Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D008780:Methyltransferases; C470732:DRM2 protein, Arabidopsis; D011495:Histone-Lysine N-Methyltransferase; C501526:SUVH2 protein, Arabidopsis