Functional characterization of IS1999, an IS4 family element involved in mobilization and expression of β-lactam resistance genes
Functional characterization of IS1999, an IS4 family element involved in mobilization and expression of β-lactam resistance genes
复制标题
DOI：
10.1128/jb.00375-06
复制
发表时间：
2006-09-01
影响因子：
3.2
通讯作者：
Nordmann, Patrice
中科院分区：
文献类型：
--
作者：
Aubert, Daniel;Naas, Thierry;Nordmann, Patrice
IS1999和一个点突变衍生物IS1999.2被描述插入新出现的抗生素耐药基因bla（VEB-1）和bla（OXA-48）的上游。cDNA末端的快速扩增实验表明，这些β -内酰胺酶基因的表达是由位于IS1999元件的外向启动子P-out驱动的。这些发现引导我们研究is1999介导的基因动员。因此，我们研究了IS1999和基于IS1999的复合转座子的转座特性，这些转座子是由IS1999在不同方向上的两个拷贝组成的。IS1999或基于IS1999的复合转座子能够转座到接合质粒pOX38-Gen上。序列分析表明，IS1999优先插入含有共识序列NGCNNNGCN的DNA靶点。当至少一个左反转重复端位于转座子的外端时，转座子的效率更高。IS1999.2的转座子频率比IS1999低10倍，而假定的天然转座子Tn1999的转座子频率低于我们的转座子检测限。逆转录pcr分析显示，基于is1999.2的元件的转座频率降低可能是由于转座酶基因的转录降低。
IS1999 and a point mutant derivative, IS1999.2, have been described inserted upstream of emerging antibiotic resistance genes bla(VEB-1) and bla(OXA-48.) 5' Rapid amplification of cDNA ends experiments revealed that expression of these beta-lactamase genes was driven by the outward-directed promoter, P-out, located in the IS1999 elements. These findings led us to study IS1999-mediated gene mobilization. Thus, the transposition properties of IS1999 and of IS1999-based composite transposons, made of two copies of IS1999 in different orientations, were investigated. IS1999 or IS1999-based composite transposons were capable of transposing onto the conjugative plasmid pOX38-Gen. Sequence analysis of the insertion sites revealed that IS1999 inserted preferentially into DNA targets containing the consensus sequence NGCNNNGCN. Transposition was more efficient when at least one left inverted repeat end was located at an outside end of the transposon. The transposition frequency of IS1999.2 was 10-fold lower than that of IS1999, and transposition frequencies of the putative natural transposon, Tn1999, were below detection limits of our transposition assay. This reduced transposition frequency of IS1999.2-based elements may result from a lower transcription of the transposase gene, as revealed by reverse transcription-PCR analyses.