期刊
MOLECULAR MICROBIOLOGY
卷 87, 期 1, 页码 1-13出版社
WILEY
DOI: 10.1111/mmi.12079
关键词
-
资金
- University of Otago
- University of Cambridge (UK)
- Health Sciences Division (University of Otago)
- Marsden Fund
- Biotechnology and Biological Sciences Research Council [BB/F009666/1, BB/H013261/1] Funding Source: researchfish
- BBSRC [BB/F009666/1, BB/H013261/1] Funding Source: UKRI
ICEMlSym(R7A) of Mesorhizobium loti is an integrative and conjugative element (ICE) that confers the ability to form a nitrogen-fixing symbiosis with Lotus species. Horizontal transfer is activated by TraR and N-acyl-homoserine lactone (AHL), which can stimulate ICE excision in 100% of cells. However, in wild-type cultures, the ICE is excised at low frequency. Here we show that QseM, a widely conserved ICE-encoded protein, is an antiactivator of TraR. Mutation of qseM resulted in TraR-dependent activation of AHL production and excision, but did not affect transcription of traR. QseM and TraR directly interacted in a bacterial two-hybrid assay in the presence of AHL. qseM expression was repressed by a DNA-binding protein QseC, which also activated qseC expression from a leaderless transcript. QseC differentially bound two adjacent operator sites, the lower affinity of which overlapped the -35 regions of the divergent qseC-qseM promoters. QseC homologues were identified on ICEs, TraR/TraM-regulated plasmids and restriction-modification cassettes, suggesting a conserved mode of regulation. Six QseC variants with distinct operators were identified that showed evidence of reassortment between mobile elements. We propose that QseC and QseM comprise a bimodal switch that restricts quorum sensing and ICEMlSym(R7A) transfer to a small proportion of cells in the population.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据