By combining physical theory with experiments on channel reconstitution into planar lipid bilayers, we concentrate on studies of mitochondrial and bacterial membrane proteins that produce “large” beta-barrel channels. These channel-forming proteins are not only the gateways of metabolite exchange between different cellular compartments and cells; they are also recognized as multifunctional membrane receptors and components of many toxins, which start to emerge as novel pharmaceutical targets. Our research serves as the basis for the development of new approaches to treatment of various diseases, wherein regulation of transport through ion channels plays the key role.
The channel-forming proteins and peptides we work with include VDAC (Voltage-Dependent Anion Channel from the outer membrane of mitochondria), alpha-Hemolysin (toxin from Staphylococcus aureus), translocation pores of B. anthracis (PA63), C. botulinum (C2IIa), and C. perfringens (Ib) binary toxins, Epsilon toxin (from Clostridium perfringens), OmpF (general bacterial porin from Escherichia coli), LamB (sugar-specific bacterial porin from Escherichia coli), OprF (porin from Pseudomonas aeruginosa), Alamethicin (amphiphilic peptide toxin from Trichoderma viride), Syringomycin E (lipopeptide toxin from Pseudomonas syringae), and the bacterial peptide TisB involved in persister cell biofilm formation. We also use Gramicidin A (linear pentadecapeptide from Bacillus brevis) as a molecular sensor of membrane mechanical properties. To study the channel-forming proteins under precisely controlled conditions, we first isolate them from the host organisms, purify, and then reconstitute them into planar lipid bilayer membranes. Our main goal is to elucidate the physical principles and molecular mechanisms which control metabolite flux under normal and pathological conditions. Specifically, we study channel interactions with the lipid membrane as modified by volatile anesthetics, with cytosolic proteins and newly synthesized drugs, such as blockers of the translocation pores of bacterial toxins. By learning the physics, chemistry, and physiology of channel functioning, we strive to determine how to design new agents and strategies that effectively correct the deviant interactions associated with disease.