Sequence analysis of Tn9 insertions in the lacZ gene.
Sequence analysis of Tn9 insertions in the lacZ gene.
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DOI：
10.1016/0022-2836(80)90213-2
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发表时间：
1980-11
影响因子：
5.6
通讯作者：
D. Galas;M. Calos;J. Miller
中科院分区：
文献类型：
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作者：
D. Galas;M. Calos;J. Miller
我们对 thelacZ 基因最后 160 个碱基对中 28 个独立出现的转座子 Tn9 的插入位点进行了测序。插入位于 16 个不同的点，其中 5 个点由多次出现表示。每个插入位点周围序列的比较表明 Tn9 插入位点处的核酸内切切割的优先但非强制性模式。观察到的最强“切割偏好”是在整合过程中重复的九个碱基对序列的每一端存在 G·C 碱基对，而没有明显考虑方向。在 28 个插入中的 23 个以及所有多次出现的位点中观察到了这一特征。一半的插入被分组在一个 16 碱基对区域内，该区域包含与 IS1 最后 7 个碱基对相同的 7 个碱基对序列，这提高了与元件末端的同源性在插入位点选择中发挥作用的可能性。本文和随附论文（Milleret al., 1980）的结论是，IS1 和 Tn9 的转座更频繁地发生在大规模的容易变性的区域中。在序列水平上，揭示了参与转座的酶的切割特异性，这可能与与元件末端同源的序列的存在协同作用，以产生观察到的插入位点的分布。
We have sequenced the sites of insertion of 28 independent occurrences of the transposon Tn9 in the final 160 base-pairs of thelacZgene. The insertions are at 16 different points, and five of these points are represented by multiple occurrences. A comparison of the sequence surrounding each of the insertion sites indicates a preferential, but not obligatory, pattern for the endonucleolytic cleavage at Tn9 insertion sites. The strongest “cutting preference” observed is the presence of a G · C base-pair, without apparent regard to orientation, at each end of the nine base-pair sequence repeated during integration. This feature was observed for 23 of the 28 insertions, and for all the sites of multiple occurrence. Half of the insertions are grouped within a 16 base-pair region that contains a seven base-pair sequence identical to the last seven base-pairs of IS1, raising the possibility that homology with the ends of the element plays a role in insertion site selection.The conclusion of this and the accompanying paper (Milleret al., 1980) is that the transposition of IS1 and Tn9 occurs more frequently into easily denaturable regions, on a large scale. At the sequence level, a cleavage specificity for the enzyme(s) involved in transposition is revealed, which may act in concert with the presence of sequences homologous to the ends of the element to produce the observed distribution of insertion sites.