Electron microscopic and biochemical evidence that chromatin structure is a repeating unit.

IF 45.5 1区生物学 Q1 BIOCHEMISTRY & MOLECULAR BIOLOGY

Cell Pub Date : 1975-04-01 DOI:10.1016/0092-8674(75)90149-x

P Oudet, M Gross-Bellard, P Chambon

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引用次数: 751

Abstract

Electron microscopic and biochemical studies demonstrate that the fundamental structure of chromatin depleted of lysine-rich histones is composed of a flexible chain of spherical particles (nucleosomes), about 125 A in diameter, connected by DNA filaments. Such a chromatin preparation can be separated by centrifugation into two fractions which differ in the spacing of the nucleosomes; In one fraction almost all of the DNA is condensed in nucleosomes, while the other fraction contains long stretches of free DNA connecting regions where the nucleosomes are closely packed. The isolated nucleosomes contain about 200 base pairs of DNA and the four histones F2alpha1, F2alpha2, and F2b, and F3 in an overall histone/DNA ratio of 0.97; In such a structure the DNA is compacted slightly more than five times from its extended length; The same basic structure can be visualized in chromatin spilling out of lysed nuclei. However, in this latter case the nucleosomes are very closely packed, suggesting that histone F1 is involved in the superpacking of DNA in chromosomes and nuclei. The chromatin fiber appears to be a self-assembling structure, since the nucleosomal arrangement can be reconstituted in vitro from DNA and the four histones F2alpha1, F2alpha2, F2b and F3 only, irrespective of their cellular origin.

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电镜和生化证据表明染色质结构是一个重复单元。

电镜和生化研究表明，缺乏富含赖氨酸的组蛋白的染色质的基本结构是由直径约125 a的球形颗粒(核小体)的柔性链组成的，由DNA细丝连接。这样的染色质制备可以通过离心分离成核小体间距不同的两个部分;在一个片段中，几乎所有的DNA都浓缩在核小体中，而另一个片段包含长段自由DNA，连接核小体紧密堆积的区域。分离得到的核小体含有约200个碱基对的DNA和4个组蛋白F2alpha1、F2alpha2、F2b和F3，组蛋白/DNA比值为0.97;在这样的结构中，DNA的压缩比其延伸长度的五倍多一点;同样的基本结构可以在染色质中看到，染色质从裂解的细胞核中溢出。然而，在后一种情况下，核小体非常紧密地包裹在一起，这表明组蛋白F1参与了染色体和细胞核中DNA的超包装。染色质纤维似乎是一种自组装结构，因为核小体的排列可以在体外由DNA和四种组蛋白F2alpha1、F2alpha2、F2b和F3重建，而不管它们的细胞起源如何。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Cell 生物-生化与分子生物学

CiteScore

110.00

自引率

0.80%

发文量

396

审稿时长

2 months

期刊介绍： Cells is an international, peer-reviewed, open access journal that focuses on cell biology, molecular biology, and biophysics. It is affiliated with several societies, including the Spanish Society for Biochemistry and Molecular Biology (SEBBM), Nordic Autophagy Society (NAS), Spanish Society of Hematology and Hemotherapy (SEHH), and Society for Regenerative Medicine (Russian Federation) (RPO). The journal publishes research findings of significant importance in various areas of experimental biology, such as cell biology, molecular biology, neuroscience, immunology, virology, microbiology, cancer, human genetics, systems biology, signaling, and disease mechanisms and therapeutics. The primary criterion for considering papers is whether the results contribute to significant conceptual advances or raise thought-provoking questions and hypotheses related to interesting and important biological inquiries. In addition to primary research articles presented in four formats, Cells also features review and opinion articles in its "leading edge" section, discussing recent research advancements and topics of interest to its wide readership.