Heterogeneity in the secondary metabolism of Photorhabdus and Xenorhabdus

抗生素等天然产物在我们的日常生活中扮演着重要的角色，但我们对其生产的调控却知之甚少。细菌NP生产者通常具有生产几种不同NP的能力，并且通常可以在给定时间生产甚至几种不同的NP衍生物。由于这需要很大比例的细胞能量和资源，因为通常涉及巨大的酶复合物，一小部分细胞只产生一小部分化合物的系统（劳动分工）可能对细菌菌落有利，因为所有细胞都可以制造和使用社区制造的所有化合物。NP基因启动子与编码荧光蛋白的基因融合的第一个实验表明，对于一些NP基因启动子，只有一小部分细胞显示出预期的荧光，使得分工模型非常可能。潜在的机制将在Photorhabdus和Xabrohabdus细菌，这是已知的生产商的几种生物活性的天然产物进行调查。使用荧光显微镜或流式细胞术，用不同的荧光报告子平行分析两个NP生物合成基因启动子（并以组成型启动子作为对照）。将通过荧光激活细胞分选（FACS）分选不同群体以研究群体稳定性。转录因子作为全球监管机构已被证明不仅影响NP生产，但也启动子的异质性和其他调节蛋白将详细投资。最后，将详细研究蒽醌（AQ）生物合成调控的生化原理。在这里，已经鉴定了一类新的转录因子，并且将分析其如何调节AQ生物合成以及其自身如何被调节，包括可能充当该转录因子的配体的NP和已经显示与相应AQ启动子结合的其他转录因子。由此产生的数据将用于与其他小组合作模拟潜在的调控机制，这些知识反过来将用于增加生物活性天然产物的生产，并增加我们对细菌异质性的了解。

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.