A new bacteroides conjugative transposon that carries an ermB gene
A new bacteroides conjugative transposon that carries an ermB gene
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DOI：
10.1128/aem.69.11.6455-6463.2003
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发表时间：
2003-11-01
影响因子：
4.4
通讯作者：
Salyers, AA
中科院分区：
文献类型：
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作者：
Gupta, A;Vlamakis, H;Salyers, AA
红霉素耐药基因ermB已在多种革兰氏阳性菌中发现。该基因也在类杆菌属物种中发现，但仅在最近分离的六个菌株中发现；因此，该基因似乎只是最近才进入该属。6株含ermB的拟杆菌菌株中有一株WH207能通过接合方式将ermB转移到BT4001菌株。根据其16S rRNA基因序列，确定WH207为一株均匀类杆菌。脉冲场凝胶电泳实验结果表明，转移元件正常整合到类杆菌染色体中。根据脉冲场凝胶数据估计该元件的大小约为100kb。由于该元件似乎是一个接合转座子(CTN)，所以命名为CTnBST。CTnBST能够将共居的质粒和可动员的转座子NBU1的环状形式动员到类杆菌和大肠杆菌受体。克隆了含有ermB的13kb片段，并进行了序列测定。该区域的大多数开放阅读框在氨基酸序列水平上与序列数据库中的任何蛋白质几乎没有相似性，但1,723个核苷酸的DNA片段(包括ermB下游的950个核苷酸片段)的DNA序列与以前在产气荚膜梭菌中发现的DNA片段几乎相同。这一发现，以及ermB位于CTN上的发现，支持了CTnBST可能从其他属进入类杆菌的假设，可能来自革兰氏阳性细菌。此外，这一发现支持了类杆菌中许多可传播的抗生素耐药基因携带在CTN上的假说。
The erythromycin resistance gene ermB has been found in a variety of gram-positive bacteria. This gene has also been found in Bacteroides species but only in six recently isolated strains; thus, the gene seems to have entered this genus only recently. One of the six Bacteroides ermB-containing isolates, WH207, could transfer ermB to Bacteroides thetaiotaomicron strain BT4001 by conjugation. WH207 was identified as a Bacteroides uniformis strain based on the sequence of its 16S rRNA gene. Results of pulsed-field gel electrophoresis experiments demonstrated that the transferring element was normally integrated into the Bacteroides chromosome. The element was estimated from pulsed-field gel data to be about 100 kb in size. Since the element appeared to be a conjugative transposon (CTn), it was designated CTnBST. CTnBST was able to mobilize coresident plasmids and the circular form of the mobilizable transposon NBU1 to Bacteroides and Escherichia coli recipients. A 13-kb segment that contained ermB was cloned and sequenced. Most of the open reading frames in this region had little similarity at the amino acid sequence level to any proteins in the sequence databases, but a 1,723-bp DNA segment that included a 950-bp segment downstream of ermB had a DNA sequence that was virtually identical to that of a segment of DNA found previously in a Clostridium perfringens strain. This finding, together with the finding that ermB is located on a CTn, supports the hypothesis that CTnBST could have entered Bacteroides from some other genus, possibly from gram-positive bacteria. Moreover, this finding supports the hypothesis that many transmissible antibiotic resistance genes in Bacteroides are carried on CTns.