Heterogeneity in the secondary metabolism of Photorhabdus and Xenorhabdus

虽然像抗生素这样的天然产物在我们的日常生活中扮演着重要的角色，但我们对它们的生产调控知之甚少。细菌NP生产者通常有能力生产几种不同的NP，并且通常在给定的时间甚至可以生产几种不同的NP的衍生物。由于通常涉及巨大的酶复合体，这需要很大比例的细胞能量和资源，因此，一种一小部分细胞只产生一小部分化合物(分工)的系统可能对细菌群体有利，因为所有细胞都可以制造和使用群落产生的所有化合物。首次将NP基因启动子与编码荧光蛋白的基因融合的实验表明，对于某些NP基因启动子，只有一小部分细胞显示出预期的荧光，这使得分工模式非常可能。将在Photorhabdus和Xnowhabdus细菌中研究潜在的机制，这两种细菌是几种生物活性天然产品的已知生产者。利用荧光显微镜或流式细胞术对两个NP生物合成基因启动子进行平行分析(并以构成启动子为对照)，使用不同的荧光报告程序。采用荧光激活细胞分选技术(FACS)对不同种群进行分选，研究种群稳定性。转录因子作为全球调节因子被证明不仅影响NP的产生，而且影响启动子的异质性，额外的调节蛋白将被详细投资。最后，我们将详细研究调节蒽醌(AQ)生物合成的生化原理。在这里，一类新的转录因子已经被发现，它如何调节AQ的生物合成以及它本身是如何被调节的，将被分析，包括可能作为这个转录因子和其他转录因子的配体的NP，这些转录因子已经被证明与各自的AQ启动子结合。所产生的数据将被用于与其他小组合作建立基本调控机制的模型，这些知识将反过来用于增加生物活性天然产品的生产，并增加我们对细菌异质性的总体知识。

Although natural products (NP) like antibiotics play an important role in our daily life we hardly know anything about the regulation of their production. Bacterial NP producers usually have the capacity to produce several different NP and often can produce even several different derivatives thereof at a given time. As this requires a large proportion of the cells energy and resources due to the often huge enzymatic complexes involved, a system in which a small fraction of cells produce only a fraction of compounds (division of labor) might be advantageous for the bacterial colony as by that all cells can make and use all compounds made by the community. First experiments with NP gene promoters fused to genes encoding fluorescence proteins showed that for some NP gene promoters only a small fraction of cells show the expected fluorescence, making a division of work model very likely. The underlying mechanisms will be investigated in Photorhabdus and Xenorhabdus bacteria, which are known producers of several bioactive natural products. Two NP biosynthesis gene promoters will be analyzed in parallel (and with a constitutive promoter as control) with different fluorescence reporters using fluorescence microscopy or flow cytometry. The different populations will be sorted by fluorescence activated cell sorting (FACS) to study the population stability. Transcription factors acting as global regulators have been shown to influence not only NP production but also promoter heterogeneity and additional regulator proteins will be invested in detail. Finally, the biochemical principles underlying the regulation of anthraquinone (AQ) biosynthesis will be studied in detail. Here, a novel class of transcription factor has already been identified and how it regulates AQ biosynthesis and how itself is regulated will be analyzed including NPs that might act as ligands for this and other transcription actors already shown to bind to the respective AQ promoter. The resulting data will be used to model the underlying regulatory mechanisms in collaboration with other groups and this knowledge in turn will be used to increase the production of bioactive natural products and to increase our knowledge of bacterial heterogeneity in general.