Φm46.1, the Main Streptococcus pyogenes Element Carrying mef(A) and tet(O) Genes
Φm46.1, the Main Streptococcus pyogenes Element Carrying mef(A) and tet(O) Genes
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DOI：
10.1128/aac.00499-09
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发表时间：
2010-01-01
影响因子：
4.9
通讯作者：
Giovanetti, Eleonora
中科院分区：
文献类型：
--
作者：
Brenciani, Andrea;Bacciaglia, Alessandro;Giovanetti, Eleonora
Phi m46.1是化脓性链球菌中最常见的携带耐药基因mef(A)和tet(O)的最常见的前噬菌体相关遗传元件变异体的代表，该基因具有外排介导的红霉素耐药性和四环素耐药性。对Phi m46.1基因组(55,172个碱基)的测序表明，尾部噬菌体具有典型的模块化结构。对丝裂霉素诱导的phi m46.1进行的电子显微镜分析显示，噬菌体颗粒具有明显的二十面体的头和尾的形态，与西波罗病毒科的家族相似。染色体整合位点位于23S rRNA尿嘧啶甲基转移酶基因内。BLASTP分析表明，该蛋白与其他前驱体蛋白的氨基酸序列具有较高的相似性，特别是化脓性链球菌的phi 10394.4和无乳链球菌的lambda Sa04。噬菌体DNA在宿主细胞中既以噬菌体形式存在，又以游离环状DNA形式存在。由于含有tet(O)(来自整合的结合元件2096-RD.2)和Mef(A)(来自Tn1207.1类转座子)的片段插入到未整合的噬菌体DNA中，溶原性模块似乎已经分裂。噬菌体附着序列位于非整合形式的tet(O)和mef(A)之间。因此，虽然在这种形式中，tet(O)类似于MEF(A)上游的5.5kb，但在整合形式中，位于前噬菌体右端附近的tet(O)类似于位于前噬菌体左端附近的Mef(A)下游的46.3kb。
Phi m46.1, the recognized representative of the most common variant of mobile, prophage-associated genetic elements carrying resistance genes mef(A) (which confers efflux-mediated erythromycin resistance) and tet(O) (which confers tetracycline resistance) in Streptococcus pyogenes, was fully characterized. Sequencing of the Phi m46.1 genome (55,172 bp) demonstrated a modular organization typical of tailed bacteriophages. Electron microscopic analysis of mitomycin-induced Phi m46.1 revealed phage particles with the distinctive icosahedral head and tail morphology of the Siphoviridae family. The chromosome integration site was within a 23S rRNA uracil methyltransferase gene. BLASTP analysis revealed that the proteins of Phi m46.1 had high levels of amino acid sequence similarity to the amino acid sequences of proteins from other prophages, especially Phi 10394.4 of S. pyogenes and lambda Sa04 of S. agalactiae. Phage DNA was present in the host cell both as a prophage and as free circular DNA. The lysogeny module appears to have been split due to the insertion of a segment containing tet(O) (from integrated conjugative element 2096-RD.2) and mef(A) (from a Tn1207.1-like transposon) into the unintegrated phage DNA. The phage attachment sequence lies in the region between tet(O) and mef(A) in the unintegrated form. Thus, whereas in this form tet(O) is similar to 5.5 kb upstream of mef(A), in the integrated form, tet(O), which lies close to the right end of the prophage, is similar to 46.3 kb downstream of mef(A), which lies close to the left end of the prophage.