Epigenetic modification of centromeric chromatin: hypomethylation of DNA sequences in the CENH3-associated chromatin in Arabidopsis thaliana and maize.
The centromere in eukaryotes is defined by the presence of a special histone H3 variant, CENH3. Centromeric chromatin consists of blocks of CENH3-containing nucleosomes interspersed with blocks of canonical H3-containing nucleosomes. However, it is not known how CENH3 is precisely deposited in the centromeres. It has been suggested that epigenetic modifications of the centromeric chromatin may play a role in centromere identity. The centromeres of Arabidopsis thaliana are composed of megabase-sized arrays of a 178-bp satellite repeat. Here, we report that the 178-bp repeats associated with the CENH3-containing chromatin (CEN chromatin) are hypomethylated compared with the same repeats located in the flanking pericentromeric regions. A similar hypomethylation of DNA in CEN chromatin was also revealed in maize (Zea mays). Hypomethylation of the DNA in CEN chromatin is correlated with a significantly reduced level of H3K9me2 in Arabidopsis. We demonstrate that the 178-bp repeats from CEN chromatin display a distinct distribution pattern of the CG and CNG sites, which may provide a foundation for the differential methylation of these repeats. Our results suggest that DNA methylation plays an important role in epigenetic demarcation of the CEN chromatin.
Zhang
Wenli
W
Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706, USA.
Lee
Hye-Ran
HR
Koo
Dal-Hoe
DH
Jiang
Jiming
J
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D020029:Base Pairing; D001483:Base Sequence; D002503:Centromere / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D019175:DNA Methylation; D018744:DNA, Plant / Q000378:metabolism; D044127:Epigenesis, Genetic; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D007399:Interphase; D008540:Meiosis; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D003313:Zea mays / Q000235:genetics*
D002843:Chromatin; D018744:DNA, Plant; D006570:Heterochromatin; D006657:Histones