Two distinct modes of nucleosome modulation associated with different degrees of dependence of nucleosome positioning on the underlying DNA sequence.
BACKGROUND
The nucleosome is the fundamental unit of eukaryotic genomes. Its positioning plays a central role in diverse cellular processes that rely on access to genomic DNA. Experimental evidence suggests that the genomic DNA sequence is one important determinant of nucleosome positioning. Yet it is less clear whether the role of the underlying DNA sequence in nucleosome positioning varies across different promoters. Whether different determinants of nucleosome positioning have characteristic influences on nucleosome modulation also remains to be elucidated.


RESULTS
We identified two typical promoter classes in yeast associated with high or low dependence of nucleosome positioning on the underlying DNA sequence, respectively. Importantly, the two classes have low or high intrinsic sequence preferences for nucleosomes, respectively. The two classes are further distinguished by multiple promoter features, including nucleosome occupancy, nucleosome fuzziness, H2A.Z occupancy, changes in nucleosome positions before and after transcriptional perturbation, and gene activity. Both classes have significantly high turnover rates of histone H3, but employ distinct modes of nucleosome modulation: The first class is characterized by hyperacetylation, whereas the second class is highly regulated by ATP-dependent chromatin remodelling.


CONCLUSIONS
Our results, coupled with the known features of nucleosome modulation, suggest that the two distinct modes of nucleosome modulation selectively employed by different genes are linked with the intrinsic sequence preferences for nucleosomes. The difference in modes of nucleosome modulation can account for the difference in the contribution of DNA sequence to nucleosome positioning between both promoter classes.
Dai
Zhiming
Z
Electronic Department, Sun Yat-Sen University, Guangzhou, PR China. zhimdai@gmail.com
Dai
Xianhua
X
Xiang
Qian
Q
Feng
Jihua
J
Wang
Jiang
J
Deng
Yangyang
Y
He
Caisheng
C
D001483:Base Sequence; D042002:Chromatin Assembly and Disassembly; D004271:DNA, Fungal / Q000235:genetics* / Q000378:metabolism*; D016681:Genome, Fungal / Q000235:genetics; D009707:Nucleosomes / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D015003:Yeasts / Q000166:cytology / Q000235:genetics
D004271:DNA, Fungal; D009707:Nucleosomes