RND-Efflux Pumps for Metal Cations
Dietrich H. Nies
from: Microbial Efflux Pumps: Current Research (Edited by: Edward W. Yu, Qijing Zhang and Melissa H. Brown). Caister Academic Press, U.K. (2013)
Abstract
This review will concentrate on metal-transporting RND-proteins in bacteria since such proteins have not been found in archaea or eucarya. Metal cations play an important role in cellular biochemistry. They are counter-ions of the negative charges in proteins, nucleic acids and phospholipids, and bridge these negative charges. Transitions metals serve as stability cores of proteins, catalyze redox reactions and rearrange small molecules. However, essential transition metal cations and those not needed by cells are toxic due to their interference with other metal cations, binding to wrong sites and dangerous redox reactions. It is therefore an interesting question how cells manage to allocate the correct metal to the right site and prevent others from doing harm. The first step into such a distribution process is a kinetic flow equilibrium of metal uptake and efflux processes that adjusts the cellular metal cation bouquet in just the right composition. Since metals may change their oxidation state or not but they cannot be degraded as organic molecules, metals are excellent subjects to understand basic homeostatic mechanisms of a living cell read more ...
