Genom-wide nucleosome positioning mechanisms in the fission yeast Schizosaccharomyces pombe

获取真核生物基因组信息的关键是通过将DNA包装到核小体中进行调节。并入核小体的DNA序列比非核小体序列更难接近。哪些分子机制决定了核小体沿着DNA的定位，这在很大程度上仍然不清楚。最近，这些机制可以通过核小体的全基因组定位以前所未有的方式进行研究。这导致了最近非常显著的“核小体定位基因组密码”的假设。我们最近生成了分裂酵母Schizosaccharomyces pombe的第一个全基因组核小体定位图，并与已发表的远亲出芽酵母Saccharomyces cerevisiae （baker’s yeast）的数据进行了全面比较。我们发现了核小体定位的显著差异，特别是在DNA序列的作用方面，并得出结论，核小体定位机制在进化上是可塑的，而不是普遍的、内在的DNA编码。由于S. pombe和S. cerevisiae之间的进化比较特别具有启示意义，并且S. pombe在染色质生物学方面比S. cerevisiae更接近多细胞真核生物，但同样容易接近，我们现在希望彻底研究S. pombe的核小体定位机制。

The access to eukaryotic genomic information is crucially regulated by the packaging of DNA into nucleosomes. DNA sequences incorporated into nucleosomes are much less accessible than non-nucleosomal sequences. It is still largely unclear which molecular mechanisms determine the positioning of nucleosomes along the DNA. Since recently, these mechanisms can be studied in unprecedented ways through the genome-wide mapping of nucleosome positions. This led recently and very prominently to the postulation of a universal “genomic code for nucleosome positioning”. We recently generated the first genome-wide nucleosome positioning map of the fission yeast Schizosaccharomyces pombe and did a comprehensive comparison with published data of the very distantly related budding yeast Saccharomyces cerevisiae (baker’s yeast). We found remarkable differences in nucleosome positioning, especially with regard to the role of DNA sequence, and conclude that nucleosome positioning mechanisms are evolutionarily plastic rather than universally and intrinsically DNA-encoded. As evolutionary comparisons between S. pombe and S. cerevisiae are especially revealing, and as S. pombe is more similar to multicellular eukaryotes with regard to chromatin biology than S. cerevisiae, but equally well accessible, we wish now to thoroughly study nucleosome positioning mechanisms in S. pombe.