Signal Transduction and Iron Transport in Bacteria
Gram negative bacteria are surrounded by a double concentric membrane system--the cytoplasmic, or inner, membrane and the outer membrane. Dr. Postle’s lab is studying a form of signal transduction in Escherichia coli: the means by which cytoplasmic membrane energy (protonmotive force) is transduced to transport proteins in the outer membrane by TonB protein. Current information indicates that energy is transduced by a series of conformational changes in cytoplasmic membrane TonB protein which are transmitted to the outer membrane transport proteins by direct physical contact. An understanding of the molecular mechanism of TonB-dependent energy transduction will provide unique insights into all signal transduction processes. Furthermore, the ability of many bacterial pathogens to obtain iron from host proteins like transferrin is a TonB-dependent process. Since pathogens lacking TonB can be compromised in their ability to cause disease, our understanding of the mechanism of TonB-dependent energy transduction can lead to the development of novel chemotherapeutics.