位點特異性重組

位點特異性重組(Site-specific recombination)是生物基因重組的一種機制,即兩段具有一定同源序列DNA發生重組[1][2][3],此過程中兩段DNA序列會發先發生聯會,位點特異性重組酶英語Recombinase(SSR)會與DNA結合,切割兩段DNA後促進酯交換反應,使一段DNA與另一段DNA連接-而形成霍利迪交叉,再進行第二次切割而得到重組過的兩段DNA[4][5]。重組酶可分為酪胺酸重組酶(如Cre重組酶英語Cre recombinaseFLP重組酶英語FLP-FRT recombination)與絲胺酸重組酶(如γδ解離酶Tn3解離酶英語Tn3 transposon)兩大類,兩者結構與詳細反應機理均不同[6][7],前者僅分別切割兩段DNA的一股,後者則將兩段共4股DNA都切割[8]

酪胺酸重組酶催化位點特異性重組的機制,上方為傳統觀點,下方為較新研究的觀點
絲胺酸重組酶催化位點特異性重組的機制,四股DNA均被切割

位點特異性重組的特異性很高[9],在DNA複製可動遺傳因子插入等過程中會發生[10],也被用作基因工程的一項技術[11]。此重組依重複片段的排列狀況可能有整合、切除與倒位三種結果,兩段不同DNA間的位點特異性重組可造成一段DNA被整合進另一段DNA中,同DNA中兩段同向序列的位點特異性重組可造成中間的序列被移除,而兩段反向序列的位點特異性重組則可造成中間序列倒位[12]

參見

參考文獻

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