Molecular mechanisms of gating ion channels and transporters in bacterial homeostasis. (360G-Wellcome-092552_C_10_Z)

We have demonstrated that mechanosensitive channels and the glutathione-gated potassium efflux systems play major roles in bacterial survival of osmotic and chemical stresses, respectively. These systems are widespread in the major Gram negative pathogens. New insights into gating have resulted from our recent work. The predictions from these studies have been tested by mutagenesis, specific assay systems and protein biochemistry. These analyses have identified new questions regarding the molec ular movements required for the formation of the open state. This analysis has also identified opportunities for the design of chemicals that interact specifically to effect either inhibition or activation, both of which perturb homeostasis. This increases their potential as drugs, either alone or in combination therapies. In the proposed research we will use crystallography, molecular genetics, protein biophysics, chemistry and electrophysiology on purified and reconstituted systems. Our spe cific goals are: elucidate the mechanism of communication between glutathione ligands and pore in KefFC determine how mechanosensitive channels interact with lipids and sense changes in membrane tension elucidate the structures of MscK and YbdG mechanosensitive channels and of KefC design, synthesis and screening of inhibitors and activators for KefC and mechanosensitive channels as research tools and potential drugs.