Extracellular pyruvate: sensing, uptake, and significance for gamma-proteobacteria

丙酮酸是一种中枢代谢物，由于代谢过度，许多细菌会将其排泄到环境中。在以前的研究中，我们发现了一个丙酮酸传感器和转运蛋白网络，它在营养限制下在大肠杆菌和其他伽马蛋白细菌中被激活，以重新摄取这种代谢物。该项目的第一部分致力于详细阐明该网络在大肠杆菌中的关键组成部分的结构和功能。研究的重点是(1)研究了大肠杆菌丙酮酸敏感组氨酸激酶/反应调节系统Btss/BtsR和YdpA/YpdB中异常的非磷酸化信号转导及其结构分析。(2)大肠杆菌的两个丙酮酸转运蛋白BstT和Csta的三维结构需要解析。这两种转运蛋白都属于研究较少的csta转运蛋白家族。Csta是该家族中的命名蛋白，将首次从底物专一性、动力学和能量化方面进行生化特征的研究。尽管丙酮酸感觉网络在伽马蛋白细菌中广泛存在，但不同属之间在设计和功能上存在显著差异。例如，弧菌属细菌的丙酮酸排泄量明显高于大肠杆菌，但有一个非常简单的丙酮酸传感和摄取系统。因此，在项目的第二部分，研究将扩展到坎贝尔氏弧菌(以前的哈维氏弧菌)，一种群体感应的模式细菌。工作重点(三)。关于坎培利弧菌丙酮酸感知和运输的生物学意义的澄清。此外，(4.)Campbellii将被用作模式生物来研究胞外丙酮酸与微生物相互作用的相关性。我们将解决这个问题，细菌是竞争丙酮酸作为营养物质，还是使用这种化合物来吸引和杀死其他物种。该项目的工作预计将有助于更好地了解初级代谢物丙酮酸的感知和吸收及其对微生物相互作用的意义。

Pyruvate, a central metabolite, is excreted by many bacteria into the environment as a result of overflow metabolism. In previous studies we identified a network of pyruvate sensors and transporters, which is activated in Escherichia coli and other gamma-proteobacteria under nutrient limitation to reuptake this metabolite. The first part of the project is dedicated to the detailed elucidation of the structure and function of key components of this network in E. coli. The studies shall focus (1.) on the investigation of the unusual phosphorylation-independent signal transduction within the pyruvate-sensing histidine kinase/response regulator systems BtsS/BtsR and YdpA/YpdB of E. coli and their structural analysis. (2.) The 3D structures of the two pyruvate transporters BstT and CstA of E. coli shall be resolved. Both transporters belong to the poorly investigated CstA transporter family. CstA, the name-giving protein of the family, will be biochemically characterized with respect to substrate specificity, kinetics and energization for the first time. Although the pyruvate sensory network is widespread in gamma-proteobacteria, there are significant differences in design and functionality among genera. For example, bacteria of the genus Vibrio excrete significantly more pyruvate than Escherichia, but have a very simple system for pyruvate sensing and uptake. Therefore, in the second part of the project, the studies will be extended to Vibrio campbellii (previously V. harveyi), a model bacterium for quorum sensing. The work shall focus (3.) on the clarification of the biological significance of pyruvate sensing and transport in V. campbellii. Furthermore, (4.) V. campbellii will be used as a model organism to investigate the relevance of extracellular pyruvate for microbial interactions. We will address the question whether bacteria compete for pyruvate as a nutrient or use the compound to attract and kill other species. Work on this project is expected to contribute to a better understanding of sensing and uptake of the primary metabolite pyruvate and its significance for microbial interactions.