Quorum-sensing regulation of a capsular polysaccharide receptor for the Rhodobacter capsulatus gene transfer agent (RcGTA)
Quorum-sensing regulation of a capsular polysaccharide receptor for the Rhodobacter capsulatus gene transfer agent (RcGTA)
复制标题
DOI：
10.1111/mmi.12132
复制
发表时间：
2013-02-01
影响因子：
3.6
通讯作者：
Beatty, J. Thomas
中科院分区：
文献类型：
--
作者：
Brimacombe, Cedric A.;Stevens, Aaron;Beatty, J. Thomas
由荚膜红杆菌（Rhodobacter capsulatus, RcGTA）产生的基因转移剂类似于一个小尾噬菌体，它可以包装几乎随机的基因组DNA片段，这些片段可以转移到其他荚膜红杆菌细胞中。基因转移剂是由许多原核生物产生的；然而，尚未发现受体。我们研究了野生型荚膜菇细胞在不同培养生长期的RcGTA受体能力，发现随着培养进入固定期，RcGTA依赖性等位基因获得的频率增加。我们还发现RcGTA对细胞的吸附也遵循类似的趋势。研究发现，GtaR/I群体感应（QS）系统对RcGTA的接收能力和吸附能力有一定的影响。胞外多糖的产生被发现受到GtaR/I QS的调节，细胞胶囊的产生也是如此。研究人员鉴定了一些可能受qs调控的多糖生物合成基因，并对其中两个基因rcc01081和rcc01932进行诱变，得到了缺乏荚膜的菌株。此外，这些突变体的RcGTA受体能力和吸附能力都受到了损害，未被封装的野生型菌株也是如此。综上所述，我们的研究结果表明，荚膜多糖是荚膜霉基因转移剂RcGTA的受体。
The gene transfer agent produced by Rhodobacter capsulatus (RcGTA) resembles a small tailed bacteriophage that packages almost random genomic DNA segments that may be transferred to other R.capsulatus cells. Gene transfer agents are produced by a number of prokaryotes; however, no receptors have been identified. We investigated the RcGTA recipient capability of wild-type R.capsulatus cells at different culture growth phases, and found that the frequency of RcGTA-dependent acquisition of an allele increases as cultures enter the stationary phase. We also found that RcGTA adsorption to cells follows a similar trend. RcGTA recipient capability and adsorption were found to be dependent on the GtaR/I quorum-sensing (QS) system. Production of an extracellular polysaccharide was found to be regulated by GtaR/I QS, as was production of the cell capsule. A number of QS-regulated putative polysaccharide biosynthesis genes were identified, and mutagenesis of two of these genes, rcc01081 and rcc01932, yielded strains that lack a capsule. Furthermore, these mutants were impaired in RcGTA recipient capability and adsorption, as was a non-encapsulated wild-type isolate of R.capsulatus. Overall, our results indicate that capsular polysaccharide is a receptor for the gene transfer agent of R.capsulatus, RcGTA.