Mechanism of energy transduction to the outer membrane of escherichia coli

我们实验室的研究计划涉及一大群被称为革兰氏阴性菌的双膜被膜或细胞壁的结构和功能。我们的研究涉及内外膜在物质通过外膜运输过程中的相互作用，以及维持双膜被膜结构和正常功能所涉及的细胞质外应激反应的生理和调节。在我们目前的研究中，我们正在研究一种蛋白质复合体的结构和作用机制，这种复合体使革兰氏阴性细菌能够输入必要的营养物质。在大肠杆菌中，TonB/ExbB/ExbD复合体被用来将铁原子输送到细胞内，用于各种细胞过程。细菌使用高度特异的运输机制来捕获铁，首先是通过将其与铁载体结合，然后通过将铁载体与外膜上的高亲和力受体结合，并将其输送到细胞内。它需要能量来完成这种通过外膜的运输，在我们的实验研究中，我们正在使用TonB的特定片段来测试关于TonB/ExbB/ExbD复合体从内膜为铁载体跨外膜运输提供能量的机制的基本假设。最近，我们还证明了参与细胞能量平衡(分解代谢抑制调节)的一组非常大的协调调节基因与另外两组基因之间的联系，这两组基因的功能是维持健康的双层膜包膜。在我们目前的研究中，我们还在更准确地确定这两组重要基因之间联系的性质。

The research programme of our laboratory is concerned with the structure and function of the double membrane envelope, or cell wall, of a large group of bacteria called the Gram negatives.  Our research deals with interactions between the inner and outer membrane in the transport of materials across the outer membrane, as well as the physiology and regulation of extracytoplasmic stress responses that are involved in maintaining the structure and proper functioning of the double membrane envelope.      In our current research, we are studying the structure and mechanism of action of a protein complex that allows Gram negative bacteria to import essential nutrients.  The TonB/ExbB/ExbD complex in Escherichia coli is used to transport iron atoms into the cell for use in a wide variety of cellular processes.  The bacteria use highly specific transport mechanisms to capture iron, first by binding it to siderophores and then by binding the siderophores to high affinity receptors in the outer membrane and transporting them into the cell. It requires energy to accomplish this transport across the outer membrane, and the TonB complex "transduces" this energy from the inner to the outer membrane.  In our experimental studies we are using specific fragments of TonB to test fundamental hypotheses about the mechanism by which the TonB/ExbB/ExbD complex provides energy from the inner membrane for the transport of siderophores across the outer membrane.        We have also recently demonstrated a link between a very large group of coordinately regulated genes involved in the energy balance of the cell (the catabolite repression regulon) and the regulation of two other groups of genes whose function is to maintain the double membrane envelope in a healthy state (the extracytoplasmic stress regulons).  In our current studies we are also determining the nature of the links between these two important groups of genes more precisely.