通过核酸酶消化研究染色质结构对DNA修复合成分布的影响。

The influence of chromatin structure on the distribution of DNA repair synthesis studied by nuclease digestion.

作者信息

Bodell W J, Banerjee M R

出版信息

Nucleic Acids Res. 1979 Jan;6(1):359-70. doi: 10.1093/nar/6.1.359.

DOI:10.1093/nar/6.1.359

PMID:424297

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC327693/

Abstract

The influence of chromatin structure on the distribution of DNA repair synthesis was studied by enzymatic digestion of "repair labeled" nuclei of mouse mammary cells: "repair labeled" nuclei were isolated from pregnancy mammary tissue fragments, treated in vitro with methylmethanesulfonate (MMS) or methylnitrosourea (MNU), and pulse-labeled with 3H-thymidine in the presence of hydroxyurea in the culture medium. Micrococcal nuclease digestion of "repair labeled" nuclei indicates that at early hours after treatment with the alkylating agents 70-80% of the total repair synthesis is located in the linker portion of the nucleosome. However, 6-12 hours after treatment DNA repair synthesis is more evenly distributed throughout the core and linker portion of the nucleosome. "Repair labeled" mammary cell nuclei were also digested with DNase I under conditions selective for transcriptionally active chromatin. A two-fold higher level of repair synthesis was found in the transcriptionally active chromatin of "repair labeled" nuclei isolated from MMS or MNU treated mammary fragments, pulse-labeled at different times after treatment. The results indicate that structural constitution of the chromatin may influence the distribution of DNA repair synthesis both at the nucleosome level, and at higher levels of chromatin organization. This may be due to 1) nonrandom base alkylation in chromatin or 2) areas in chromatin with increased accessibility for the repair enzymes to the alkylated bases.

摘要

通过对小鼠乳腺细胞“修复标记”细胞核进行酶消化，研究了染色质结构对DNA修复合成分布的影响：“修复标记”细胞核从小鼠妊娠乳腺组织片段中分离出来，体外经甲磺酸甲酯（MMS）或甲基亚硝基脲（MNU）处理，然后在培养基中存在羟基脲的情况下用³H - 胸腺嘧啶脉冲标记。对“修复标记”细胞核进行微球菌核酸酶消化表明，在用烷化剂处理后的早期，总修复合成的70 - 80%位于核小体的连接区。然而，处理后6 - 12小时，DNA修复合成在核小体的核心区和连接区分布更为均匀。“修复标记”的乳腺细胞核也在对转录活性染色质具有选择性的条件下用DNase I进行消化。在从MMS或MNU处理的乳腺片段中分离出的、在处理后不同时间进行脉冲标记的“修复标记”细胞核的转录活性染色质中，发现修复合成水平高出两倍。结果表明，染色质的结构组成可能在核小体水平以及更高层次的染色质组织水平上影响DNA修复合成的分布。这可能是由于1）染色质中碱基的非随机烷基化，或2）染色质中修复酶对烷基化碱基可及性增加的区域。