Recognition of DNA insertion/deletion mismatches by an activity in Saccharomyces cerevisiae.
Recognition of DNA insertion/deletion mismatches by an activity in Saccharomyces cerevisiae.
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DOI：
10.1093/nar/24.4.721
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发表时间：
1996-02
影响因子：
14.9
通讯作者：
J. Miret;B. Parker;R. S. Lahua
中科院分区：
文献类型：
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作者：
J. Miret;B. Parker;R. S. Lahua
cerevisiae核提取物中的活性与一条链中含有4至9个额外碱基的异双链特异性结合。这种活性（IMR，插入错配识别）在带移分析中的特异性通过竞争实验得到证实。IMR在生化和遗传学上不同于依赖于MSH2的单碱基错配结合活性。这两种活性在电泳过程中迁移不同，竞争不同，错配结合谱也不同。此外，在msh2- msh3- msh4-菌株的提取物中观察到IMR活性。IMR在两种不同的序列背景下表现出插入错对的特异性。绑定受不匹配结构的影响，因为带有发夹配置的插入不能被此活动识别。IMR不是由单链结合产生的，因为单链探针不能产生IMR复合物，而单链竞争者无法从复合物中置换插入的异双工。本质上弯曲的双相化合物的类似结果使识别不太可能仅由弯曲赋予。由IMR结合的异源双链不含任何明显的损伤。这些发现与酵母含有一种独特的识别因子IMR的观点是一致的，IMR是插入/删除不匹配的特异性。
An activity in nuclear extracts of S.cerevisiae binds specifically to heteroduplexes containing four to nine extra bases in one strand. The specificity of this activity (IMR, for insertion mismatch recognition) in band shift assays was confirmed by competition experiments. IMR is biochemically and genetically distinct from the MSH2 dependent, single base mismatch binding activity. The two activities migrate differently during electrophoresis, they are differentially competable and their spectra of mispair binding are distinct. Furthermore, IMR activity is observed in extracts from an msh2- msh3- msh4- strain. IMR exhibits specificity for insertion mispairs in two different sequence contexts. Binding is influenced by the structure of the mismatch since an insertion with a hairpin configuration is not recognized by this activity. IMR does not result from single-strand binding because single-stranded probes to not yield IMR complex and single-stranded competitors are unable to displace insertion heteroduplexes from the complex. Similar results with intrinsically bent duplexes make it unlikely that recognition is conferred by a bend alone. Heteroduplexes bound by IMR do not contain any obvious damage. These findings are consistent with the idea that yeast contains a distinct recognition factor, IMR that is specific for insertion/deletion mismatches.