P1BPUMPS · Structural and functional characterization of molecular nanomachines: principles of transition metal selectivity and transport in heavy metal P1B-type ATPases

Cellular concentrations of transition metals are tightly regulated to a necessary balance to satisfy essential requirements for the activity of fundamental biochemical processes and avoid toxic levels which would impair cell survival. P1B-type ATPases are a family of membrane ion pumps which utilize the energy generated by ATP hydrolysis to drive the selective heavy metal translocation across the cellular membrane against the electrochemical gradient. Although playing a pivotal role in regulating the concentrations of essential physiological metal elements (e.g: Cu, Zn) and toxic transition metals (e.g.: Cd, Pb), the mechanism by which these molecular machines perform their function are not understood in detail. The proposed project aims to reveal at a molecular level the principles and determinants for heavy metal selectivity, metal binding geometry, metal translocation pathway, and energy transduction processes in energy-driven metal transport in P1B-type ATPases. A complementary X-ray crystallographic and biochemical approach will be developed in order to obtain a molecular understanding of the three-dimensional structure and the function of prokaryotic P1B-type ATPases. The final goal is to reveal how these molecular machines convert the energy stored in ATP into conformational changes which result into directional transport of heavy metal across the lipid bilayer. Elucidating the mechanism of transition metal transport across biological membranes accomplished by P1B-type ATPases will shed light on an essential biochemical process conserved in all the kingdoms of life and will provide the bases for the future rational design of modulators of P1B-type ATPase activity.