DNA超螺旋
拓扑异构酶
DNA
染色质
DNA复制
真核细胞DNA复制
生物物理学
复制蛋白A
HMG盒
劈理(地质)
抄写(语言学)
生物
细胞生物学
DNA钳
化学
分子生物学
生物化学
转录因子
DNA结合蛋白
基因
逆转录酶
核糖核酸
古生物学
语言学
哲学
断裂(地质)
出处
期刊:Cancer drug discovery and develogment
日期:2011-08-26
卷期号:: 53-69
被引量:1
标识
DOI:10.1007/978-1-4614-0323-4_2
摘要
Human topoisomerase I (Top1) catalyzes the reversible cleavage of one strand of DNA to provide swivels to relax the supercoils associated with DNA replication, transcription, and chromatin assembly. The cleavage reaction occurs with the covalent attachment of an active-site tyrosine to the 3′ end of the broken strand; religation restores continuity to the DNA and releases the enzyme. During the cleaved state, relaxation of torsionally strained supercoils occurs by a controlled rotation mechanism. X-ray crystal structures of the enzyme with bound DNA combined with single-molecule experiments provide insights into the chemistry, specificity, and dynamics of the DNA relaxation process. A failure of Top1 to carry out religation at DNA lesions or in the presence of drugs such as camptothecin causes DNA damage that must be repaired if the cell is to survive. The list of proteins known to interact with Top1 suggests that the enzyme has functions in vivo that extend well beyond the previously characterized roles in replication, transcription, and chromatin assembly.
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