SITE-SPECIFIC INSERTION OF GENES INTO INTEGRONS - ROLE OF THE 59-BASE ELEMENT AND DETERMINATION OF THE RECOMBINATION CROSS-OVER POINT
SITE-SPECIFIC INSERTION OF GENES INTO INTEGRONS - ROLE OF THE 59-BASE ELEMENT AND DETERMINATION OF THE RECOMBINATION CROSS-OVER POINT
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DOI：
10.1111/j.1365-2958.1991.tb00817.x
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发表时间：
1991-08-01
影响因子：
3.6
通讯作者：
STOKES, HW
中科院分区：
文献类型：
--
作者：
HALL, RM;BROOKES, DE;STOKES, HW
通过对已发表的插入整合子中特定位点的基因的DNA序列的检查，显示所有基因在其3'端与短的不完全反向重复序列、59个碱基的元件或该元件的相对元件相关。描述了在整合子和Tn7转座子家族中基因插入物的排列的相似性。一个完善的共识为59基地的元素报告。这个家庭的成员是高度分歧和一组较长的元素的59个碱基的元素的关系被证明。不同长度和序列的59个碱基元件作为整合子编码的DNA整合酶催化重组的位点的能力被证明，证实了这个家族的元件具有共同的功能。位于基因对之间的元件作为重组位点的能力也已得到证实。重组交叉点定位于GTT三联体，其在核心位点GTTRRRY中是保守的，在59个碱基元件的3'端发现。在59碱基元件的5'端，未检测到反向的核心位点的突变，而负责重组事件方向的序列似乎位于59碱基元件内，提出了整合子和Tn7类转座子的基因位点特异性插入模型。由与59个碱基元件相关的基因组成的环状单元插入既不含基因也不含59个碱基元件的祖先元件中。可以在由第一基因插入事件产生的复合位点中的一个或两个处插入另外的基因。实验衍生的共整合体的int依赖性分辨率的证据表明，DNA整合酶催化切除以及插入事件的能力。这一发现与位点特异性重组通过在新位点切除和重新插入而在基因传播中的第二个作用是一致的。
From examination of published DNA sequences of genes found inserted at a specific site in integrons, all genes are shown to be associated, at their 3' ends, with a short imperfect inverted repeat sequence, a 59-base element or relative of this element. The similarity of the arrangement of gene inserts in the integron and in the Tn7 transposon family is described. A refined consensus for the 59-base element is reported. Members of this family are highly diverged and the relationship of a group of longer elements to the 59-base elements is demonstrated. The ability of 59-base elements of different length and sequence to act as sites for recombination catalysed by the integron-encoded DNA integrase is demonstrated, confirming that elements of this family have a common function. The ability of elements located between gene pairs to act as recombination sites has also been demonstrated. The recombination cross-over point has been localized to the GTT triplet which is conserved in the core sites, GTTRRRY, found at the 3' end of 59-base elements. Recombination at the core site found in inverse orientation at the 5' end of the 59-base elements was not detected, and the sequences responsible for orientation of the recombination event appear to reside within the 59-base element.A model for site-specific insertion of genes into integrons and Tn7-like transposons is proposed. Circular units consisting of a gene associated with a 59-base element are inserted into an ancestral element which contains neither a gene nor a 59-base element. Further genes can be inserted at one or both of the composite sites generated by the first gene-insertion event. Evidence for int-dependent resolution of experimentally derived cointegrates demonstrates the ability of the DNA integrase to catalyse excision as well as insertion events. This finding is consistent with a second role for site-specific recombination in the spread of genes by excision and reinsertion at new sites.