位点特异性重组

位点特异性重组(Site-specific recombination)是生物基因重组的一种机制,即两段具有一定同源序列DNA发生重组[1][2][3],此过程中两段DNA序列会发先发生联会,位点特异性重组酶英语Recombinase(SSR)会与DNA结合,切割两段DNA后促进酯交换反应,使一段DNA与另一段DNA连接-而形成霍利迪交叉,再进行第二次切割而得到重组过的两段DNA[4][5]。重组酶可分为酪胺酸重组酶(如Cre重组酶英语Cre recombinaseFLP重组酶英语FLP-FRT recombination)与丝胺酸重组酶(如γδ解离酶Tn3解离酶英语Tn3 transposon)两大类,两者结构与详细反应机理均不同[6][7],前者仅分别切割两段DNA的一股,后者则将两段共4股DNA都切割[8]

酪胺酸重组酶催化位点特异性重组的机制,上方为传统观点,下方为较新研究的观点
丝胺酸重组酶催化位点特异性重组的机制,四股DNA均被切割

位点特异性重组的特异性很高[9],在DNA复制可动遗传因子插入等过程中会发生[10],也被用作基因工程的一项技术[11]。此重组依重复片段的排列状况可能有整合、切除与倒位三种结果,两段不同DNA间的位点特异性重组可造成一段DNA被整合进另一段DNA中,同DNA中两段同向序列的位点特异性重组可造成中间的序列被移除,而两段反向序列的位点特异性重组则可造成中间序列倒位[12]

参见

参考文献

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