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Updated: Feb 2, 2026
Assembly of Nucleosomal Arrays from Recombinant Core Histones and Nucleosome Positioning DNA
Published on: September 10, 2013
N6-methyldeoxyadenosine directs nucleosome positioning in Tetrahymena DNA
Guan-Zheng Luo1,2,3, Ziyang Hao4,5, Liangzhi Luo4,5,6
1The State Key Laboratory of Biocontrol, MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510060, China. luogzh5@mail.sysu.edu.cn.
Background:
N6-methyldeoxyadenosine (6mA or m6dA) was shown more than 40 years ago in simple eukaryotes. Recent studies revealed the presence of 6mA in more prevalent eukaryotes, even in vertebrates. However, functional characterizations have been limited.
Results:
We use Tetrahymena thermophila as a model organism to examine the effects of 6mA on nucleosome positioning. Independent methods reveal the enrichment of 6mA near and after transcription start sites with a periodic pattern and anti-correlation relationship with the positions of nucleosomes. The distribution pattern can be recapitulated by in vitro nucleosome assembly on native Tetrahymena genomic DNA but not on DNA without 6mA. Model DNA containing artificially installed 6mA resists nucleosome assembling compared to unmodified DNA in vitro. Computational simulation indicates that 6mA increases dsDNA rigidity, which disfavors nucleosome wrapping. Knockout of a potential 6mA methyltransferase leads to a transcriptome-wide change of gene expression.
Conclusions:
These findings uncover a mechanism by which DNA 6mA assists to shape the nucleosome positioning and potentially affects gene expression.
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