NUCLEOSOME POSITIONING ON THE MMTV LTR RESULTS FROM THE FREQUENCY-BIASED OCCUPANCY OF MULTIPLE FRAMES
NUCLEOSOME POSITIONING ON THE MMTV LTR RESULTS FROM THE FREQUENCY-BIASED OCCUPANCY OF MULTIPLE FRAMES
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DOI：
10.1101/gad.9.15.1933
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发表时间：
1995-08-01
影响因子：
10.5
通讯作者：
HAGER, GL
中科院分区：
文献类型：
--
作者：
FRAGOSO, G;JOHN, S;HAGER, GL
在高分辨率下确定了小鼠乳腺肿瘤病毒（MMTV）启动子区核小体的翻译位置。核小体边界在引物延伸测定中使用从用甲醛（一种可逆的蛋白质-DNA交联剂）处理的细胞制备的全长单链单核细胞体DNA来确定。在启动子的核小体A（Nuc-A）和Nuc-B区域都观察到多个边界，表明多个核小体翻译框架。Nuc-A和Nuc-B区的不同核小体框架被不均匀地占据。发现最频繁占用的帧彼此聚集在50-60个碱基内，导致分布集中在先前在低分辨率下定义的Nuc-A和Nuc-B的位置。在B区中，发现最丰富的5'端在-235和-187之间，3'端在-86和-36之间，而在A区中，最丰富的5'端在-22和+42之间，3'端在+121和+186之间。尽管LTR的Nuc-B区域中的框架在朝向Nuc-C区域的5'方向上以低频率延伸，但在朝向Nuc-A的3'方向上存在明显的不连续性，表明在A-B接头中存在边界约束。当用地塞米松激活启动子时，核小体框架在B或A区的位置和相对占据率没有改变。
The translational positions of nucleosomes in the promoter region of the mouse mammary tumor virus (MMTV) were defined at high resolution. Nucleosome boundaries were determined in primer extension assays using full-length single-stranded mononucleosomal DNA prepared from cells treated with formaldehyde, a reversible protein-DNA cross-linking agent. Multiple boundaries were observed in both the nucleosome A (Nuc-A) and Nuc-B region of the promoter, indicating multiple nucleosome translational frames. The different nucleosome frames in both the Nuc-A and Nuc-B regions were occupied unequally. The most frequently occupied frames were found clustered within 50-60 bases of each other, resulting in a distribution centered in the positions defined previously at low resolution for Nuc-A and Nuc-B. The most abundant 5' ends of the frames in the B region were found between -235 and -187, and the 3' ends between -86 and -36, whereas in the A region the most abundant 5' ends were between -22 and +42, and the 3' ends between +121 and +186. Although frames in the Nuc-B region of the LTR extend at a low frequency in the 5' direction toward the Nuc-C region, there is a sharp discontinuity in the 3' direction toward Nuc-A, suggesting the presence of a boundary constraint in the A-B linker. The positions and relative occupancies of nucleosome frames, in either the B or the A region, did not change when the promoter was activated with dexamethasone.