Investigation of the Genetics and Biochemistry of Roseobacticide Production in the Roseobacter Clade Bacterium Phaeobacter inhibens.
Investigation of the Genetics and Biochemistry of Roseobacticide Production in the Roseobacter Clade Bacterium Phaeobacter inhibens.
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DOI：
10.1128/mbio.02118-15
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发表时间：
2016-03-22
期刊：
影响因子：
6.4
通讯作者：
Seyedsayamdost MR
中科院分区：
文献类型：
--
作者：
Wang R;Gallant É;Seyedsayamdost MR
蔷薇枝细菌在地表沃茨中含量丰富，是代谢多样性和生态重要性最高的物种之一。这一组包括机会共生体，与微型和大型藻类。我们已经提出，一个代表性的成员，Phaeoprostenbens，从事一个动态的共生与microemiliania huxleyi。在一个阶段，互惠互利的分子交换，包括玫瑰杆菌产生的抗生素tropodiethetic酸（TDA），这被认为是保护共生相互作用。在另一个寄生阶段，由藻类衰老引发，细菌产生有效的杀藻剂，即杀玫瑰杆菌剂，杀死藻类宿主。在这里，我们采用遗传和生物化学筛选来鉴定rosebacticide生物合成基因簇。通过使用转座子诱变的方法，我们发现，TDA合成所需的基因tda操纵子和paa分解代谢物也是必要的rosebacticide生产。因此，与一簇一化合物的模式相反，tda基因簇可以产生两组具有不同结构和生物活性的分子。我们进一步表明，rosebacticide的生产是通过N-酰基高丝氨酸内酯信号（3-OH-C10-HSL）的群体感应调节。为了确保杀藻剂生产的严格调节，从而从共生到寄生的生活方式转换，rosebobacticide生物合成需要藻类衰老分子和群体感应信号的存在。海洋蔷薇科物种在海洋中非常丰富，并与微观藻类进行共生相互作用。其中一个成员，P. lubens，产生抗生素TDA和生长激素，被认为是保护和促进藻类生长。然而，在衰老藻类释放的分子存在的情况下，细菌产生有效的杀藻剂，即杀死宿主的杀藻剂。我们研究了rosebacticide生产所需的调控网络和生物合成基因。我们发现，P. lubens在很大程度上使用相同的一组基因来生产TDA和rosebobacticides，从而提供了一种罕见的情况，其中一个基因簇合成两种结构和功能不同的分子。此外，我们发现rosebacticide的生产受到群体感应的调节。因此，两个小分子，藻类代谢物和群体感应信号，确保严格控制生产rosobacticides。这些结果突出了小分子在调节微生物共生中的作用。
Roseobacter clade bacteria are abundant in surface waters and are among the most metabolically diverse and ecologically significant species. This group includes opportunistic symbionts that associate with micro- and macroalgae. We have proposed that one representative member, Phaeobacter inhibens, engages in a dynamic symbiosis with the microalga Emiliania huxleyi. In one phase, mutualistically beneficial molecules are exchanged, including the Roseobacter-produced antibiotic tropodithietic acid (TDA), which is thought to protect the symbiotic interaction. In an alternative parasitic phase, triggered by algal senescence, the bacteria produce potent algaecides, the roseobacticides, which kill the algal host. Here, we employed genetic and biochemical screens to identify the roseobacticide biosynthetic gene cluster. By using a transposon mutagenesis approach, we found that genes required for TDA synthesis—the tda operon and paa catabolon—are also necessary for roseobacticide production. Thus, in contrast to the one-cluster–one-compound paradigm, the tda gene cluster can generate two sets of molecules with distinct structures and bioactivities. We further show that roseobacticide production is quorum sensing regulated via an N-acyl homoserine lactone signal (3-OH–C10-HSL). To ensure tight regulation of algaecide production, and thus of a lifestyle switch from mutualism to parasitism, roseobacticide biosynthesis necessitates the presence of both an algal senescence molecule and a quorum sensing signal. Marine Roseobacter species are abundant in the oceans and engage in symbiotic interactions with microscopic algae. One member, P. inhibens, produces the antibiotic TDA and a growth hormone thought to protect and promote algal growth. However, in the presence of molecules released by senescing algae, the bacteria produce potent algaecides, the roseobacticides, which kill the host. We examined the regulatory networks and biosynthetic genes required for roseobacticide production. We found that P. inhibens uses largely the same set of genes for production of both TDA and roseobacticides, thus providing a rare case in which one gene cluster synthesizes two structurally and functionally distinct molecules. Moreover, we found roseobacticide production to be regulated by quorum sensing. Thus, two small molecules, the algal metabolite and the quorum-sensing signal, ensure tight control in the production of roseobacticides. These results highlight the role of small molecules in regulating microbial symbioses.