Identification of A Novel Arsenic Resistance Transposon Nested in A Mercury Resistance Transposon of Bacillus sp. MB24
Identification of A Novel Arsenic Resistance Transposon Nested in A Mercury Resistance Transposon of Bacillus sp. MB24
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DOI：
10.3390/microorganisms7110566
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发表时间：
2019-11
期刊：
影响因子：
4.5
通讯作者：
Mei-fang Chien;Ying-Ning Ho;Hui-Erh Yang;M. Narita;K. Miyauchi;G. Endo;Chieh-Chen Huang
中科院分区：
文献类型：
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作者：
Mei-fang Chien;Ying-Ning Ho;Hui-Erh Yang;M. Narita;K. Miyauchi;G. Endo;Chieh-Chen Huang
从水俣湾沉积物中分离的耐汞芽孢杆菌中鉴定出一个新的TnMERI 1样转座子TnMARS 1。两个相邻的ars操纵子样基因簇，ars 1和ars 2，侧翼由一对78 bp的反向重复序列，这导致了一个13.8 kbp的转座子样片段，被发现夹在两个转座基因的TnMERI 1-like转座子的耐汞细菌，芽孢杆菌MB 24。5′-RACE结果表明，两个簇中均存在一个转录起始位点，表明两个簇都是操纵子。真实的实时定量RT-PCR结果表明，砷对各操纵子中arsR基因的转录均有诱导作用，arsR 2对砷的反应比arsR 1更敏感、更显著。此外，砷抗性互补实验表明，ars 2操纵子赋予砷酸盐和亚砷酸盐抗性的arsB敲除芽孢杆菌宿主，而ars 1操纵子仅轻微提高亚砷酸盐抗性。这种嵌套在TnMARS 1中的转座子被命名为TnARS 1。针对细菌和芽孢杆菌全基因组序列数据库的多基因簇blast表明，TnMARS 1是第一例TnMERI 1样转座子与砷抗性转座子结合的情况。这项研究的结果表明，TnMERI 1-like转座子可以招募其他移动的元素到其遗传结构，并随后导致水平传播的汞和砷的细菌在水俣湾。
A novel TnMERI1-like transposon designated as TnMARS1 was identified from mercury resistant Bacilli isolated from Minamata Bay sediment. Two adjacent ars operon-like gene clusters, ars1 and ars2, flanked by a pair of 78-bp inverted repeat sequences, which resulted in a 13.8-kbp transposon-like fragment, were found to be sandwiched between two transposable genes of the TnMERI1-like transposon of a mercury resistant bacterium, Bacillus sp. MB24. The presence of a single transcription start site in each cluster determined by 5′-RACE suggested that both are operons. Quantitative real time RT-PCR showed that the transcription of the arsR genes contained in each operon was induced by arsenite, while arsR2 responded to arsenite more sensitively and strikingly than arsR1 did. Further, arsenic resistance complementary experiments showed that the ars2 operon conferred arsenate and arsenite resistance to an arsB-knocked out Bacillus host, while the ars1 operon only raised arsenite resistance slightly. This transposon nested in TnMARS1 was designated as TnARS1. Multi-gene cluster blast against bacteria and Bacilli whole genome sequence databases suggested that TnMARS1 is the first case of a TnMERI1-like transposon combined with an arsenic resistance transposon. The findings of this study suggested that TnMERI1-like transposons could recruit other mobile elements into its genetic structure, and subsequently cause horizontal dissemination of both mercury and arsenic resistances among Bacilli in Minamata Bay.