The sequence of a conjugative plasmid, pSRC22-2, found in a multiply antibiotic resistant Salmonella enterica serovar Ohio isolate SRC22 originally cultured from swine in 1999, was determined. Plasmid pSRC22-2 has a copy number of approximately 40 and transfers tetracycline resistance at very high frequency. It was typed as IncX1 using the three typing schemes proposed for X-type plasmids, which utilize the replication region, iteron region and taxC conjugation gene and pSRC22-2 belongs to the X1α subgroup. The plasmid backbone, derived by removing mobile elements, is shared with pOLA52, which was the first fully sequenced IncX1 plasmid, and five other X1α plasmids. The pSRC22-2 backbone is interrupted by a complete copy of an IS903 isoform, partial copies of IS1 and IS903 on either side of a 5930 bp IS26-bounded pseudo-compound transposon (PCT), and a novel 256 bp miniature inverted repeat transposable element (MITE). The MITE belongs to the Tn3 family and was named MITESen1. The PCT, which carries a tet(C) tetracycline resistance determinant, is bounded by copies of a novel IS26 variant, IS26-v4, and was designated PTn6184. Comparison of PTn6184 with other tet(C)-carrying PCTs revealed that it can be derived from the largest, PTntet(C), via a two-step process that re-orders the central fragment and involves both an IS26-mediated event and homologous recombination. IS26-v4, which encodes a variant transposase, Tnp26 G184D, has appeared in only 46 entries in the GenBank non-redundant database.

确定了在 1999 年最初从猪中培养的多抗生素耐药性肠沙门氏菌血清型俄亥俄州分离株 SRC22 中发现的接合质粒 pSRC22-2 的序列。质粒 pSRC22-2 的拷贝数约为 40，并以非常高的频率转移四环素抗性。使用为 X 型质粒提出的三种分型方案将其分型为 IncX1，利用复制区、iteron 区和taxC结合基因，pSRC22-2 属于 X1α 亚群。通过去除移动元件衍生出的质粒骨架与 pOLA52（第一个完全测序的 IncX1 质粒）和其他五个 X1α 质粒共享。pSRC22-2 主干被 IS 903的完整副本中断同工型、5930 bp IS 26 有界假化合物转座子 (PCT)两侧IS 1和 IS 903 的部分拷贝，以及新型 256 bp 微型反向重复转座因子 (MITE)。MITE属于Tn 3家族，被命名为MITESen1。携带tet (C) 四环素抗性决定簇的 PCT受到新型 IS 26变体 IS 26 -v4的拷贝的限制，并被命名为 PTn 6184。PTn 6184与其他携带tet (C) 的 PCT 的比较表明，它可以从最大的 PTn tet (C) 中通过重新排序中心片段的两步过程，包括 IS 26介导的事件和同源重组。IS 26 -v4 编码变体转座酶 Tnp26 G184D，仅出现在 GenBank 非冗余数据库的 46 个条目中。