Salih F, Salih B, Kogan S, Trifonov E N
Genome Diversity Center, Institute of Evolution, University of Haifa, Israel.
J Biomol Struct Dyn. 2008 Aug;26(1):9-16. doi: 10.1080/07391102.2008.10507219.
Alu sequences carry periodical pattern with CG dinucleotides (CpG) repeating every 31-32 bases. Similar distances are observed in distribution of DNA curvature in crystallized nucleosomes, at positions +/-1.5 and +/-4.5 periods of DNA from nucleosome DNA dyad. Since CG elements are also found to impart to nucleosomes higher stability when positioned at +/-1.5 sites, it suggests that CG dinucleotides may play a role in modulation of the nucleosome strength when the CG elements are methylated. Thus, Alu sequences may harbor special epigenetic nucleosomes with methylation-dependent regulatory functions. Nucleosome DNA sequence probe is suggested to detect locations of such regulatory nucleosomes in the sequences.
Alu序列具有周期性模式，其中CG二核苷酸（CpG）每31 - 32个碱基重复一次。在结晶核小体中DNA曲率的分布中也观察到类似的距离，位于核小体DNA二分体的DNA的+/-1.5和+/-4.5周期位置处。由于发现CG元件位于+/-1.5位点时也会赋予核小体更高的稳定性，这表明当CG元件甲基化时，CG二核苷酸可能在调节核小体强度中发挥作用。因此，Alu序列可能含有具有甲基化依赖性调节功能的特殊表观遗传核小体。建议使用核小体DNA序列探针来检测序列中此类调节核小体的位置。
