Adolf-Butenandt-Institut, University of Munich, Munich, Germany.
Nat Struct Mol Biol. 2010 Feb;17(2):251-7. doi: 10.1038/nsmb.1741. Epub 2010 Jan 31.
Positioned nucleosomes limit the access of proteins to DNA and implement regulatory features encoded in eukaryotic genomes. Here we have generated the first genome-wide nucleosome positioning map for Schizosaccharomyces pombe and annotated transcription start and termination sites genome wide. Using this resource, we found surprising differences from the previously published nucleosome organization of the distantly related yeast Saccharomyces cerevisiae. DNA sequence guides nucleosome positioning differently: for example, poly(dA-dT) elements are not enriched in S. pombe nucleosome-depleted regions. Regular nucleosomal arrays emanate more asymmetrically-mainly codirectionally with transcription-from promoter nucleosome-depleted regions, but promoters harboring the histone variant H2A.Z also show regular arrays upstream of these regions. Regular nucleosome phasing in S. pombe has a very short repeat length of 154 base pairs and requires a remodeler, Mit1, that is conserved in humans but is not found in S. cerevisiae. Nucleosome positioning mechanisms are evidently not universal but evolutionarily plastic.
定位核小体限制了蛋白质与 DNA 的相互作用，并实现了真核基因组中编码的调控特征。在这里，我们生成了第一个全基因组核小体定位图谱，用于裂殖酵母，并注释了全基因组的转录起始和终止位点。利用这一资源，我们发现与先前发表的亲缘关系较远的酵母酿酒酵母的核小体组织有惊人的差异。DNA 序列对核小体定位的指导作用不同：例如，多聚（dA-dT）元件在裂殖酵母的核小体耗竭区域并不富集。从启动子核小体耗竭区域出发，规则的核小体阵列主要呈同向发散——主要是同向发散，但含有组蛋白变体 H2A.Z 的启动子也在这些区域的上游显示出规则的核小体阵列。裂殖酵母中规则的核小体相位具有非常短的重复长度 154 个碱基，并且需要一个重塑酶 Mit1，该酶在人类中保守，但在酿酒酵母中不存在。核小体定位机制显然不是普遍的，而是具有进化的可塑性。
