Abstract：
ISCR28 is a fully functional and active member of the IS91-like family of insertion sequences. ISCR28 is 1,708-bp long and contains a 1,293-bp long putative open reading frame that codes a transposase. Sixty ISCR28-containing sequences from GenBank generated 27 non-repeat genetic contexts, all of which represented naturally occurring biological events that had occurred in a wide range of gram-negative organisms. Insertion of ISCR28 into target DNA preferred the presence of a 5\'-GXXT-3\' sequence at its terIS (replication terminator) end. Loss of the first 4 bp of its oriIS (origin of replication) likely caused ISCR28 to be trapped in ISApl1-based transposons or similar structures. Loss of terIS and fusion with a mobile element upstream likely promoted co-transfer of ISCR28 and the downstream resistance genes. ArmA and its downstream intact ISCR28 can be excised from recombinant pKD46 plasmids forming circular intermediates, further elucidating its activity as a transposase.
摘要：
ISCR28是IS91样插入序列家族的全功能和活性成员。ISCR28长1,708-bp，包含一个1,293-bp长的推定开放阅读框，编码转座酶。来自GenBank的60个包含ISCR28的序列产生了27个非重复遗传背景，所有这些都代表了在广泛的革兰氏阴性生物中发生的自然发生的生物事件。将ISCR28插入靶DNA优选在其terIS(复制终止子)末端存在5'-GXXT-3'序列。其oriIS（复制起点）的前4bp的丢失可能导致ISCR28被困在基于ISApl1的转座子或类似结构中。terIS的丢失和与上游可移动元件的融合可能会促进ISCR28和下游抗性基因的共转移。可以从重组pKD46质粒中切除ArmA及其下游完整的ISCR28，形成环状中间体，进一步阐明其作为转座酶的活性。
