Lauderdale J D, Stein A
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Biochemistry. 1993 Jan 19;32(2):489-99. doi: 10.1021/bi00053a013.
Histone H5 induces extensive nucleosome alignment in vitro, with a 210 +/- 5 base pair (bp) average unit repeat, on some of the constructs derived from plasmid pBR327. Plasmid pBR327 itself aligns nucleosomes poorly, even though it possesses a chromatin organizing region which nucleates the alignment reaction [Jeong et al. (1991) J. Mol. Biol. 222, 1131-1147]. Examination of various regions of pBR327 chromatin by Southern hybridization revealed no substantial regional differences, suggesting an essentially all-or-none alignment mechanism. Twenty-four pBR327 deletion constructs, with the chromatin organizing region intact, were analyzed for nucleosome alignment in vitro, in addition to the six previously described. Although nucleosome alignment on plasmids of size greater than 5 kb was not affected by small length changes, circular plasmids with total lengths between 2400 and 3600 bp generally permitted alignment only when their lengths were close to integer multiples of 210 +/- 3 bp. The measured repeat lengths for the large plasmids and the smaller ones that aligned nucleosomes were all 210 bp, within experimental precision. The failure of two approximately 3.2-kb plasmids to align nucleosomes, even though their lengths were close to 15 x 210 bp, could be attributed to the effects of four strongly positioned nucleosomes that form on pBR327 sequences. Evidence is provided that nucleosome arrays can be quasicrystalline and are capable of transmitting information over a distance of more than 2 kb.
组蛋白H5在体外可诱导广泛的核小体排列，在一些源自质粒pBR327的构建体上，平均单位重复长度为210±5碱基对（bp）。质粒pBR327本身对核小体的排列效果较差，尽管它拥有一个能引发排列反应的染色质组织区域[Jeong等人（1991年）《分子生物学杂志》222卷，1131 - 1147页]。通过Southern杂交对pBR327染色质的各个区域进行检测，未发现明显的区域差异，这表明其排列机制基本上是全或无的。除了之前描述的六个构建体之外，还对24个染色质组织区域完整的pBR327缺失构建体进行了体外核小体排列分析。虽然大小大于5 kb的质粒上的核小体排列不受小长度变化的影响，但总长度在2400至3600 bp之间的环状质粒通常只有在其长度接近210±3 bp的整数倍时才允许排列。在实验精度范围内，大质粒和能排列核小体的较小质粒的测量重复长度均为210 bp。两个大约3.2 kb的质粒未能排列核小体，尽管它们的长度接近15×210 bp，这可能归因于在pBR327序列上形成的四个定位很强的核小体的影响。有证据表明核小体阵列可以是准晶体，并且能够在超过2 kb的距离上传递信息。
