Anaerobic transport in Escherichia coli membrane vesicles

Abstract

Anaerobic lactose and/or amino acid transport by membrane vesicles prepared from Escherichia coli ML 308-225 can be coupled to at least four electron transfer systems: alpha-glycerol-P-dehydrogenase:nitrate reductase, formate dehydrogenase:nitrate reductase, alpha-glycerol-P dehydrogenase:fumarate reductase, and formate dehydrogenase:fumarate reductase. Vesicles contain one or more of these electron transfer systems depending on the growth conditions of the parent cells. alpha-Glycerol-P dehydrogenase and fumarate reductase are present only in vesicles prepared from cells grown in the presence of glycerol or fumarate, respectively. Formate dehydrogenase and nitrate reductase activities, on the other hand, are present in vesicles from cells grown on a variety of media. alpha-Glycerol-P and formate are able to drive aerobic transport in vesicles prepared from anaerobically grown cells, indicating coupling between aerobic and anaerobic electron transfer systems.