Aerobic sn-Glycerol-3-phosphate dehydrogenase from Escherichia coli binds to the cytoplasmic membrane through an amphipathic α-helix

Abstract

sn-Glycerol-3-phosphate dehydrogenase (G1pD) from Escherichia coli is a peripheral membrane enzyme involved in respiratory electron transfer. For it to display its enzymic activity, binding to the inner membrane is required. The way the enzyme interacts with the membrane and how this controls activity has not been elucidated. In the present study we provide evidence for direct protein-lipid interaction. Using the monolayer technique, we observed insertion of G1pD into lipid monolayers with a clear preference for anionic phospholipids. G1pD variants with point mutations in their predicted amphipathic helices showed a decreased ability to penetrate anionic phospholipid monolayers. From these data we propose that membrane binding of G1pD occurs by insertion of an amphipathic helix into the acyl-chain region of lipids mediated by negatively charged phospholipids.