4] Binding protein-dependent ABC transport system for glycerol 3-phosphate of Escherichia coli

Abstract

Publisher Summary This chapter discusses the uptake glycerol phosphate (Ugp) system and compares it with the maltose system. It also discusses the function of binding protein (BP)-dependent adenosine triphosphate-binding cassette (ABC) transport systems. sn -Glycerol 3-phosphate (G3P) is an essential intermediate in the biosynthesis of phospholipids. When Escherichia coli grows on a carbon source other than G3P, it synthesizes it by the NADH-dependent reduction of glyceraldehyde 3-phosphate. The presence of G3P in the medium results in its uptake and direct utilization as a lipid precursor. G3P is also a carbon source. It enters glycolysis by its oxidation to dihydroxyacetone phosphate. The major uptake system for G3P is the glp regulon-dependent and glp T-encoded GIpT transport system. It is a secondary transport system in which the inward movement of G3P is coupled to the outward movement of inorganic phosphate (P i ). When growing on minimal media containing P i at concentrations >1 mM, the GlpT transport system is the only G3P transport system and glp T mutants cannot grow on G3P as the sole source of carbon.