Acyl-coenzyme A organizes laterally in membranes and is recognized specifically by acyl-coenzyme A binding protein

Long chain acyl-coenzyme A (acyl-CoA) is a biochemically important amphiphilic molecule that is known to partition strongly into membranes by insertion of the acyl chain. At present, microscopically resolved evidence is lacking on how acyl-CoA influences and organizes laterally in membranes. By atomic force microscopy (AFM) imaging of membranes exposed to acyl-CoA in muM concentrations, it is shown that aggregate formation takes place within the membrane upon long-time exposure. It is known that acyl-CoA is bound by acyl-CoA binding protein (ACBP) with high affinity and specificity and that ACBP may bind and desorb membrane-bound acyl-CoA via a partly unknown mechanism. Following incubation with acyl-CoA, it is shown that ACBP is able to reverse the formation of acyl-CoA aggregates and to associate peripherally with acyl-CoA on the membrane surface. Our microscopic results point to the role of ACBP as an intermembrane transporter of acyl-CoA and demonstrate the ability of AFM to reveal the remodelling of membranes by surfactants and proteins. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.