Microbial formate metabolism
Formate production is a means by which many anaerobic microorganisms divest themselves of excessive reducing equivalents. However, with a standard redox potential (Eh) of roughly -418 mV, formate is also a valuable source of energy. Intracellular accumulation of formate can lead to uncoupling of the membrane potential and therefore organisms that produce or consume formate require a means of controlling transport of this weak organic acid. We study the archetype of the FNT (formate and nitrite transporter) superfamily of pentameric membrane channel proteins, FocA, in E. coli. FNT proteins transport small anions, such as formate, nitrite or hydrosulfide, into and/or out of cells of uni-cellular microorganisms. They likely represent an evolutionarily ancient form of transport proteins. FocA allows anaerobically growing E. coli to export or import formate and the cytoplasmic protein pyruvate formate-lyase (PflB) has an important function in controlling FocA’s transport activity. Our research focuses on how PflB influences bi-directional formate transport by FocA and how these transport processes impact the physiology of the cell.
