IS26 forms cointegrates using two distinct routes, a copy-in mechanism involving one insertion sequence (IS) and a target and a targeted conservative mechanism involving two ISs in different DNA molecules. In this study, the ability of IS26 and some close relatives, IS1006, IS1008, and a natural hybrid, IS1006/IS1008, which are found predominantly in Acinetobacter spp., to interact was examined. IS1006/1008 consists of 175 bp from IS1006 at the left end, with the remainder from IS1008. These ISs all have the same 14-bp terminal inverted repeats, and the Tnp26, Tnp1006, and Tnp1008 transposases, with pairwise identities of 83.7% to 93.1%, should be able to recognize each other’s ends. In a recA-negative Escherichia coli strain, IS1006, IS1008, and IS1006/1008 each formed cointegrates via the copy-in route and via the targeted conservative route, albeit at frequencies for the targeted reaction at least 10-fold lower than for IS26. However, using mixed pairs, targeted cointegration was detected only when IS1008 was paired with the IS1006/1008 hybrid, which also encodes Tnp1008, and the targeted cointegrates formed all arose from a reaction occurring at the end where the DNA sequences are identical. The reaction also occurred at the end with extended DNA identity using IS26 paired with IS26::catA1, an artificially constructed IS26 derivative that includes the catA1 gene. Thus, both identical transposases and identical DNA sequences at the reacting end were required. These features indicate that the targeted conservative pathway proceeds via a single transposase-catalyzed strand transfer, followed by migration and resolution of the Holliday junction formed.

中文翻译：

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由 IS26 家族成员介导的靶向保守协整形成需要反应端的序列同一性

IS 26使用两种不同的途径形成共整合，一种涉及一个插入序列 (IS) 和一个目标的拷贝机制，以及一种涉及不同 DNA 分子中两个 IS 的靶向保守机制。在这项研究中，检查了 IS 26和一些近亲 IS 1006、IS 1008和天然杂交体 IS 1006/IS1008（主要在不动杆菌属中发现）相互作用的能力。IS 1006/1008由左端IS 1006的 175 bp 组成，其余部分来自 IS 1008。这些 IS 都具有相同的 14 bp 末端反向重复序列，Tnp26、Tnp1006 和 Tnp1008 转座酶具有 83.7% 至 93.1% 的成对身份，应该能够识别彼此的末端。在recA阴性大肠杆菌菌株中，IS 1006、IS 1008和 IS 1006/1008各自通过复制途径和靶向保守途径形成共整合，尽管靶向反应的频率至少比对于 IS 26。然而，使用混合对，只有当 IS 1008与 IS 1006 / 1008配对时才检测到目标协整杂种，它也编码 Tnp1008，并且形成的靶向共整合体都来自发生在 DNA 序列相同的末端的反应。该反应还在末端发生使用IS延伸的DNA同一性26与配对IS 26 :: catA1，人工构建的IS 26衍生物，其中包括catA1基因。因此，在反应末端需要相同的转座酶和相同的 DNA 序列。这些特征表明靶向保守途径通过单个转座酶催化的链转移进行，随后形成霍利迪连接点的迁移和分辨率。