Mechanism of energy transduction to the outer membrane of escherichia coli

我们实验室的研究项目是关于被称为革兰氏阴性菌的一大群细菌的双膜包膜或细胞壁的结构和功能。我们的研究涉及物质通过外膜运输时内外膜之间的相互作用，以及参与维持双膜包膜结构和正常功能的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物的结构和作用机制，这种蛋白质复合物允许革兰氏阴性菌进口必需的营养物质。大肠杆菌中的TonB/ExbB/ExbD复合体用于将铁原子运输到细胞中，用于各种细胞过程。细菌使用高度特异性的运输机制来捕获铁，首先将其与铁载体结合，然后将铁载体与外膜上的高亲和力受体结合，并将其运输到细胞中。它需要能量来完成这种跨外膜的运输，而TonB复合体将这种能量从内膜“转导”到外膜。在我们的实验研究中，我们使用TonB的特定片段来测试关于TonB/ExbB/ExbD复合物从内膜为铁载体通过外膜运输提供能量的机制的基本假设。我们最近还证明了一组参与细胞能量平衡的协调调节基因（分解代谢物抑制调节基因）与另外两组基因的调节之间的联系，这些基因的功能是维持双膜包膜处于健康状态（胞质外应激调节基因）。在我们目前的研究中，我们也在更精确地确定这两组重要基因之间联系的本质。

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.