Wang Hui, Tomasch Jürgen, Michael Victoria, Bhuju Sabin, Jarek Michael, Petersen Jörn, Wagner-Döbler Irene
Helmholtz-Centre for Infection Research, Microbial Communication Braunschweig, Germany.
German Collection of Microorganisms and Cell Cultures, Microbial Ecology and Diversity Research Braunschweig, Germany.
Front Microbiol. 2015 Nov 13;6:1262. doi: 10.3389/fmicb.2015.01262. eCollection 2015.
The co-cultivation of the alphaproteobacterium Dinoroseobacter shibae with the dinoflagellate Prorocentrum minimum is characterized by a mutualistic phase followed by a pathogenic phase in which the bacterium kills aging algae. Thus it resembles the "Jekyll-and-Hyde" interaction that has been proposed for other algae and Roseobacter. Here, we identified key genetic components of this interaction. Analysis of the transcriptome of D. shibae in co-culture with P. minimum revealed growth phase dependent changes in the expression of quorum sensing, the CtrA phosphorelay, and flagella biosynthesis genes. Deletion of the histidine kinase gene cckA which is part of the CtrA phosphorelay or the flagella genes fliC or flgK resulted in complete lack of growth stimulation of P. minimum in co-culture with the D. shibae mutants. By contrast, pathogenicity was entirely dependent on one of the extrachromosomal elements of D. shibae, the 191 kb plasmid. The data show that flagella and the CtrA phosphorelay are required for establishing mutualism and prove a cell density dependent killing effect of D. shibae on P. minimum which is mediated by an unknown factor encoded on the 191 kb plasmid.
α-变形菌迪氏玫瑰杆菌（Dinoroseobacter shibae）与微小原甲藻（Prorocentrum minimum）的共培养具有一个互利共生阶段，随后进入致病阶段，在此阶段细菌会杀死衰老的藻类。因此，它类似于针对其他藻类和玫瑰杆菌提出的“杰基尔与海德”式相互作用。在这里，我们确定了这种相互作用的关键遗传成分。对与微小原甲藻共培养的迪氏玫瑰杆菌转录组的分析揭示了群体感应、CtrA磷酸化信号传导和鞭毛生物合成基因表达中与生长阶段相关的变化。缺失作为CtrA磷酸化信号传导一部分的组氨酸激酶基因cckA或鞭毛基因fliC或flgK，导致与迪氏玫瑰杆菌突变体共培养时微小原甲藻完全缺乏生长刺激作用。相比之下，致病性完全取决于迪氏玫瑰杆菌的一种染色体外元件，即191 kb质粒。数据表明，鞭毛和CtrA磷酸化信号传导是建立共生关系所必需的，并证明了迪氏玫瑰杆菌对微小原甲藻具有细胞密度依赖性杀伤作用，这种作用由191 kb质粒上编码的未知因子介导。
