EVIDENCE FOR NATURAL GENE-TRANSFER FROM GRAM-POSITIVE COCCI TO ESCHERICHIA-COLI
EVIDENCE FOR NATURAL GENE-TRANSFER FROM GRAM-POSITIVE COCCI TO ESCHERICHIA-COLI
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DOI：
10.1128/jb.170.4.1739-1745.1988
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发表时间：
1988-04-01
影响因子：
3.2
通讯作者：
COURVALIN, P
中科院分区：
文献类型：
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作者：
BRISSONNOEL, A;ARTHUR, M;COURVALIN, P
大肠杆菌BM 2570对大环内酯-林可酰胺-链阳性菌素B型（MLS）抗生素的高水平耐药性是由于接合质粒pIP 1527上存在MLS耐药决定簇ermBC，该决定簇与先前在来自血链球菌的质粒pAM 77（ermAM）和来自粪肠球菌的转座子Tn 917（ermB）中描述的cR基因几乎相同。该基因及其调控区位于插入序列IS 15右端的最后37个碱基对的下游;这37个碱基对位于插入序列IS 1的下游。由pIP 1527编码的23 S rRNA甲基化酶分别与由Tn 917和pAM 77编码的23 S rRNA甲基化酶不同3个和6个氨基酸。与赋予诱导型MLS表型的链球菌元件不同，ermBC基因在E.大肠杆菌和枯草芽孢杆菌，由于在调控区的几个突变。ermBC基因的转录起始于三个不同的位点，这三个位点位于三个重叠的启动子之后，这三个启动子在E. coli和B.枯草杆菌。启动子P2和P3位于与pAM 77和Tn 917同源的区域，P1是由分别位于IS 15末端和链球菌区域中的-35和-10序列构成的杂合启动子。这些结果构成了最近从链球菌属体内转移的证据。与大肠杆菌这种转移可能是由转座子介导的，如来自肺炎链球菌的Tn 917或Tn 1545，它们也携带与ermB同源的MLS决定簇。我们推测插入序列IS 15和IS 1可能在ermBC的表达和传播中发挥作用，ermBC已在许多肠杆菌菌株中发现。
High-level resistance to macrolide-lincosamide-streptogramin type B (MLS) antibiotics in Escherichia coli BM2570 is due to the presence on the conjugative plasmid pIP1527 of the MLS resistance determinant ermBC, which is almost identical to the erm genes previously described in plasmid pAM77 from Streptococcus sanguis (ermAM) and in transposon Tn917 from Enterococcus faecalis (ermB). This gene and its regulatory region are located downstream from the last 37 base pairs of the right end of insertion sequence IS15; these 37 base pairs are located downstream from the insertion sequence IS1. The 23S rRNA methylase encoded by pIP1527 differs by three and six amino acids from those encoded by Tn917 and pAM77, respectively. Unlike the streptococcal elements which confer the inducible MLS phenotype, the ermBC gene is expressed constitutively in E. coli and Bacillus subtilis, due to several mutations in the regulatory region. Transcription of the ermBC gene starts from three different sites following three overlapping promoters which function in both E. coli and B. subtilis. Promoters P2 and P3 are located with the region homologous to pAM77 and Tn917, and P1 is a hybrid promoter constituted by -35 and -10 sequences located at the end of IS15 and in the streptococcal region, respectively. These results constitute evidence for the recent in vivo transfer from Streptococcus spp. to E. coli. This transfer could have been mediated by transposons such as Tn917 or Tn1545 from Streptococcus pneumoniae, which also bears an MLS determinant that is homologous to ermB. We speculate that the insertion sequences IS15 and IS1 could have played a role in the expression and dissemination of ermBC, which has been found in numerous strains of enterobacteria.