RT Journal
A1 Ramachandran, Srinivas
A1 Zentner, Gabriel E.
A1 Henikoff, Steven
T1 Asymmetric nucleosomes flank promoters in the budding yeast genome
JF Genome Research 
JO Genome Research 
YR 2015 
FD March 01 
VO 25 
IS 3 
SP 381 
OP 390 
DO 10.1101/gr.182618.114 
UL http://genome.cshlp.org/content/25/3/381.abstract 
AB Nucleosomes in active chromatin are dynamic, but whether they have distinct structural conformations is unknown. To identify nucleosomes with alternative structures genome-wide, we used H4S47C-anchored cleavage mapping, which revealed that 5% of budding yeast (Saccharomyces cerevisiae) nucleosome positions have asymmetric histone-DNA interactions. These asymmetric interactions are enriched at nucleosome positions that flank promoters. Micrococcal nuclease (MNase) sequence-based profiles of asymmetric nucleosome positions revealed a corresponding asymmetry in MNase protection near the dyad axis, suggesting that the loss of DNA contacts around H4S47 is accompanied by protection of the DNA from MNase. Chromatin immunoprecipitation mapping of selected nucleosome remodelers indicated that asymmetric nucleosomes are bound by the RSC chromatin remodeling complex, which is required for maintaining nucleosomes at asymmetric positions. These results imply that the asymmetric nucleosome-RSC complex is a metastable intermediate representing partial unwrapping and protection of nucleosomal DNA on one side of the dyad axis during chromatin remodeling.