Genetic structure of four plasmids found in Acinetobacter baumannii isolate D36 belonging to lineage 2 of global clone 1
Genetic structure of four plasmids found in Acinetobacter baumannii isolate D36 belonging to lineage 2 of global clone 1
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DOI：
10.1371/journal.pone.0204357
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发表时间：
2018-09-27
期刊：
影响因子：
3.7
通讯作者：
Hall, Ruth M.
中科院分区：
文献类型：
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作者：
Hamidian, Mohammad;Hall, Ruth M.
对广泛抗生素耐药的鲍曼不动杆菌分离株 D36（属于全局克隆 1 谱系 2）中发现的四种大小从 4.7 到 44.7 kb 不等的质粒进行了检查。 D36 包括两个隐秘质粒和两个携带抗生素抗性基因的质粒。最小的质粒 pD36-1 (4.7 kb) 不携带抗性基因，但包含与 pRAY* (pD36-2, 6,078 bp) 中发现的相关的 mobA 和 mobC 动员基因，pRAY* 还携带 aadB 庆大霉素、卡那霉素和妥布霉素抗性基因盒。这两个质粒不编码 Rep 蛋白。发现质粒 pRAY* 被大接合质粒 pA297-3 高频动员，但缺少 mobA 和 mobC 基因的 pRAY* 衍生物则不然。两个较大的质粒 pD36-3 和 pD36-4 编码 Rep_3 家族蛋白 (Pfam1051)。神秘质粒 pD36-3 (6.2 kb) 具有 RepAci1，而 pD36-4 (44.7 kb) 编码两个新的 Rep_3 家族蛋白，表明存在共整合。质粒 pD36-4 包括 sul2 磺酰胺抗性基因、Tn4352::ISAba1 中的 aphA1a 卡那霉素/新霉素抗性基因以及杂合 Tn501/Tn1696 转座子中赋予汞离子抗性的 mer 模块。侧翼为 pdif 位点（XerC-XerD 结合位点）的 dif 模块的新例子也在 pD36-3 和 pD36-4 中被鉴定，它们分别携带三个和两个 dif 模块，pdif 位点是许多鲍曼不动杆菌质粒的一部分。三个dif模块的同源物，即pD36-3中的sup硫酸盐通透酶模块，以及pD36-4中的abkAB毒素-抗毒素模块和orf模块，在不同不动杆菌质粒的不同环境中被发现，这与模块迁移性一致。在 abkAB dif 模块中的 pdif 位点旁边发现了一个名为 ISAba32 的新插入序列，它与 ISAjo2 组的成员有关，这些成员也与 dif 模块的 pdif 位点相关。在 D36 中发现的质粒也在 GC1 谱系 2 的一些其他成员中也被发现。
Four plasmids ranging in size from 4.7 to 44.7 kb found in the extensively antibiotic resistant Acinetobacter baumannii isolate D36 that belongs to lineage 2 of global clone 1 were examined. D36 includes two cryptic plasmids and two carrying antibiotic resistance genes. The smallest plasmid pD36-1 (4.7 kb) carries no resistance genes but includes mobA and mobC mobilisation genes related to those found in pRAY* (pD36-2, 6,078 bp) that also carries the aadB gentamicin, kanamycin and tobramycin resistance gene cassette. These two plasmids do not encode a Rep protein. Plasmid pRAY* was found to be mobilised at high frequency by the large conjugative plasmid pA297-3 but a pRAY* derivative lacking the mobA and mobC genes was not. The two larger plasmids, pD36-3 and pD36-4, encode Rep_3 family proteins (Pfam1051). The cryptic plasmid pD36-3 (6.2 kb) has RepAci1 and pD36-4 (44.7 kb) encodes two novel Rep_3 family proteins suggesting a co-integrate. Plasmid pD36-4 includes the sul2 sulfonamide resistance gene, the aphA1a kanamycin/neomycin resistance gene in Tn4352::ISAba1 and a mer module in a hybrid Tn501/Tn1696 transposon conferring resistance to mercuric ions. New examples of dif modules flanked by pdif sites (XerC-XerD binding sites) that are part of many A. baumannii plasmids were also identified in pD36-3 and pD36-4 which carry three and two dif modules, respectively. Homologs of three dif modules, the sup sulphate permease module in pD36-3, and of the abkAB toxin-antitoxin module and the orf module in pD36-4, were found in different contexts in diverse Acinetobacter plasmids, consistent with module mobility. A novel insertion sequence named ISAba32 found next to the pdif site in the abkAB dif module is related to members of the ISAjo2 group which also are associated with the pdif sites of dif modules. Plasmids found in D36 were also found in some other members of GC1 lineage 2.