Smith S S, Baker D J
Department of Cell and Tumor Biology, City of Hope National Medical Center, Duarte, California 91010-3000, USA.
Biochem Biophys Res Commun. 1997 May 8;234(1):73-8. doi: 10.1006/bbrc.1997.6581.
We describe evidence for a sequence of events in which the Human DNA(cytosine-5)methyl-transferase first methylates spontaneous single-stranded conformers (SSCs) and then stalls at the methylated site to produce a complex with the conformationally unusual DNA. This property of the enzyme is a result of its ability to respond to a general loss of symmetry at its CG recognition site. The data suggest that DNA methyltransferase, itself, may physically participate in biological processes that distinguish between DNA that is in the normal Watson-Crick paired conformation and DNA that is conformationally unusual (e.g. a hairpin loop or misassembled replication intermediate). The in vitro methylation of spontaneous SSCs from the Huntington's locus illustrates the phenomenon.
我们描述了一系列事件的证据，其中人类DNA（胞嘧啶-5）甲基转移酶首先甲基化自发单链构象体（SSCs），然后在甲基化位点停滞，以产生与构象异常的DNA形成的复合物。该酶的这一特性是其能够响应CG识别位点对称性普遍丧失的结果。数据表明，DNA甲基转移酶本身可能在区分处于正常沃森-克里克配对构象的DNA和构象异常的DNA（如发夹环或错误组装的复制中间体）的生物学过程中发挥物理作用。来自亨廷顿基因座的自发SSCs的体外甲基化说明了这一现象。
