Nucleotide sequence and transfer properties of two novel types of Actinobacillus pleuropneumoniae plasmids carrying the tetracycline resistance gene tet(H)
Nucleotide sequence and transfer properties of two novel types of Actinobacillus pleuropneumoniae plasmids carrying the tetracycline resistance gene tet(H)
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DOI：
10.1093/jac/dkm293
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发表时间：
2007-10-01
影响因子：
5.2
通讯作者：
Navas, Jesus
中科院分区：
文献类型：
--
作者：
Blanco, Monica;Kadlec, Kristina;Navas, Jesus
目的：分析胸膜肺炎放线杆菌临床分离株中发现的两种四环素耐药质粒的序列和转移特性，以评估它们在四环素耐药传播中的作用。方法：从胸膜肺炎放线杆菌中纯化质粒 p9956 和 p12494 并进行完整测序。通过电穿孔和/或接合到多杀性巴氏杆菌和大肠杆菌中来评估两种质粒的转移特性。结果：两种质粒均显示出由涉及动员、四环素抗性或复制的三个区域组成的模块化结构。动员区域包括编码松弛酶的mobA基因，松弛酶是一种参与质粒转移的蛋白质。四环素耐药区密切相关，由tet(H)基因及其阻遏基因tetR组成。通过质粒电穿孔，四环素抗性表型成功转移至多杀性假单胞菌，对于 p9956，也成功转移至大肠杆菌。此外，借助RP4接合转移功能，质粒p9956可以在大肠杆菌中移动。结论：首次测定了胸膜肺炎放线菌两个携带tet(H)的质粒的全序列。这两种质粒彼此不同，并且与已知的来自巴斯德氏菌或曼海姆氏菌属的携带tet(H)的质粒不同。结构分析证实，这些质粒由先前在巴氏杆菌科和肠杆菌科成员中检测到的片段组成。
Objectives: To analyse the sequence and transfer properties of two tetracycline resistance plasmids found in clinical isolates of Actinobacillus pleuropneumoniae in order to assess their role in the spread of tetracycline resistance.Methods: The plasmids designated p9956 and p12494 were purified from A. pleuropneumoniae and completely sequenced. The transfer properties of both plasmids were evaluated by electroporation and/or conjugation into Pasteurella multocida and Escherichia coli.Results: Both plasmids showed a modular structure consisting of three regions involved in mobilization, tetracycline resistance or replication. The mobilization regions included the mobA gene, encoding a relaxase, a protein involved in plasmid transfer. The tetracycline resistance regions were closely related and consisted of the tet( H) gene and its repressor gene tetR. The tetracycline resistance phenotype was transferred successfully to P. multocida and in the case of p9956 also to E. coli by electroporation of the plasmids. Moreover, plasmid p9956 could be mobilized in E. coli with the assistance of RP4 conjugal transfer functions.Conclusions: For the first time, the complete sequences of two tet( H)-carrying plasmids from A. pleuropneumoniae were determined. These two plasmids differed from one another and from known tet( H)- carrying plasmids from Pasteurella or Mannheimia spp. Structural analysis confirmed that these plasmids consisted of segments that have been previously detected in members of the families Pasteurellaceae and Enterobacteriaceae.