Multi drug resistance in cancer; ATP synthesis in bacteria and mitochondria.
(1) Multidrug resistance in cancer. Cancer chemotherapy often fails because the tumor develops resistance to multiple drugs simultaneously. The culprit is multidrug-resistance protein (mdr) also known as P-glycoprotein. It is located in plasma membranes, and uses ATP to transport drugs out of cells. We have generated a cell line which greatly overexpresses mdr, from which enriched plasma membranes and purified protein are readily obtained. The long-term goal is to learn ways to disable or circumvent mdr protein in cancer cells.
(2) ATP synthesis and hydrolysis in F1Fo-ATP synthase. ATP synthase is the smallest known rotary motor. It uses subunit rotation to drive ATP synthesis, and ATP hydrolysis to drive subunit rotation. The subunit rotation is linked in turn to utilization or generation of a membrane proton gradient. We are using a variety of probes to study the mechanism of catalysis and to elucidate the molecular linkage between catalysis and subunit rotation. We use the E. coli enzyme and a range of molecular genetics, biochemical and biophysical techniques. In recent work we have focussed on application of fluoroscent probes of cataytic sites which have yielded rapid and sensitive information about mechanism.