Hobman J, Kholodii G, Nikiforov V, Ritchie D A, Strike P, Yurieva O
Department of Genetics and Microbiology, Donnan Laboratories, University of Liverpool, UK.
Gene. 1994 Aug 19;146(1):73-8. doi: 10.1016/0378-1119(94)90835-4.
Three different, independently isolated mercury-resistance-conferring plasmids, pMER327/419, pMER330 and pMER05, from cultures originating from the river Mersey (UK), contain identical regulatory merR genes and transposon ends. The mer determinant from pMER327/419 contains an additional potential ORF (ORF F) located between merP and merA when compared with the archetypal Tn501. Although these plasmids confer narrow-spectrum resistance (resistance to Hg2+, but not organomercurials) their merR genes encode a potential organomercurial-sensing protein. Transposition of the mer of pMER05 into plasmid RP4 was demonstrated and, as with Tn502 and Tn5053, insertion occurred at a specific region. The sequence of pMER05 is identical at the 'left' and 'right' termini and across merR to Tn5053, which was independently isolated from the chromosome of a Xanthomonas sp. bacteria from the Khaidarkan mercury mine in Kirgizia, former Soviet Union [Kholodii et al., J. Mol. Biol. 230 (1993a) 1103-1107]. The transpositional unit of pMER05 is, like that of Tn5053, bounded by DNA homologous to the imperfect 25-bp inverted repeats (IR) of the In2 integron, which brackets antibiotic-resistance cassettes in Tn21 subgroup transposons. At one end of the transposable element, and internal to the In2-like IR, is a 38-bp IR which closely resembles the IR that bounds Tn21.
从源自英国默西河的培养物中分离出的三种不同的、独立的赋予汞抗性的质粒pMER327/419、pMER330和pMER05，含有相同的调控merR基因和转座子末端。与原型Tn501相比，pMER327/419的汞决定簇在merP和merA之间包含一个额外的潜在开放阅读框（ORF F）。尽管这些质粒赋予窄谱抗性（对Hg2+有抗性，但对有机汞化合物无抗性），但其merR基因编码一种潜在的有机汞感应蛋白。已证明pMER05的mer转座到质粒RP4中，并且与Tn502和Tn5053一样，插入发生在一个特定区域。pMER05在“左”端和“右”端以及跨越merR的序列与Tn5053相同，Tn5053是从前苏联吉尔吉斯斯坦Khaidarkan汞矿的一种黄单胞菌属细菌的染色体中独立分离出来的[Kholodii等人，《分子生物学杂志》230（1993a）1103 - 1107]。pMER05的转座单位与Tn5053的转座单位一样，由与In2整合子的不完美25碱基对反向重复序列（IR）同源的DNA界定，In2整合子在Tn21亚组转座子中包围抗生素抗性盒。在转座元件的一端，且在类似In2的IR内部，是一个38碱基对的IR，它与界定Tn21的IR非常相似。
