CHARACTERIZATION OF RAT-LIVER OLIGONUCLEOSOMES ENRICHED IN TRANSCRIPTIONALLY ACTIVE GENES - EVIDENCE FOR ALTERED BASE COMPOSITION AND A SHORTENED NUCLEOSOME REPEAT
CHARACTERIZATION OF RAT-LIVER OLIGONUCLEOSOMES ENRICHED IN TRANSCRIPTIONALLY ACTIVE GENES - EVIDENCE FOR ALTERED BASE COMPOSITION AND A SHORTENED NUCLEOSOME REPEAT
复制标题
DOI：
10.1021/bi00528a036
复制
发表时间：
1981-01-01
期刊：
影响因子：
2.9
通讯作者：
RIGGS, EA
中科院分区：
文献类型：
--
作者：
BERKOWITZ, EM;RIGGS, EA
用一种改进的微球菌核酸酶分离程序分离和分离了一个转录活性的寡核小体大小的染色质部分。在温和的酶消化后，裂解大鼠肝细胞核，用线性蔗糖梯度离心法分离染色质。来自4个梯度区域的分数被汇集在一起，并从上到下分别标记为A、B、C和D。组分A，含有.ltoreq.总DNA的20%，被确定具有六核小体的平均大小。通过与从细胞质总Poly(A)mRNA转录的[~3H]c[互补]DNA杂交，组分A的DNA转录基因比总DNA丰富10-15倍。这一组分还具有较高浓度的AT碱基序列。在核小体时相上观察到显著差异。组分A的重复长度最短，组分B和C居中，组分D在转录DNA序列中耗尽，组分D的重复长度最长。分离到一个寡核小体大小的染色质组分，富含转录基因，并以减少的核小体间距组织起来。
A transcriptionally active chromatin fraction of oligonucleosome size was separated and isolated by a modified micrococcal nuclease fractionation procedure. After mild enzymatic digestion, rat liver nuclei were lysed, and the chromatin was separated by centrifugation on linear sucrose gradients. Fractions from 4 regions of the gradient were pooled and labeled, from the top to the bottom, A, B, C and D, respectively. Fraction A, which contained .ltoreq. 20% of the total DNA, was determined to have a mean size of a hexanucleosome. By hybridization with [3H]c[complementary]DNA transcribed from total cytoplasmic poly(A) mRNA, DNA from fraction A was shown to be 10- to 15-fold enriched in transcribing genes when compared with total DNA. This fraction also has a somewhat higher concentration of AT base sequences. Significant differences were observed in nucleosome phasing. Fraction A has the shortest repeat length, fractions B and C are intermediate, and fraction D, which is depleted in transcribing DNA sequences, has the longest. A chromatin fraction of oligonucleosome size enriched in transcribing genes and organized with reduced nucleosome spacing was isolated.