Structural and Functional Consequences of Acylation of a Transmembrane Peptide

In this minireview we summarize our studies on the consequences of acylation for the structure and function of the transmembrane helical peptide gramicidin A. It is shown that acylation of the C-terminal ethanolamine group does not largely affect the polypeptide structure and conformation. However, the lifetime of the cation specific channels formed in black lipid membranes is greatly increased upon acylation. The conformation of the covalently attached acyl chain in bilayers of dimyristoylphosphatidylcholine was analyzed by 2H NMR in oriented systems using palmitoylgramicidin in which the acyl chain was either per- or specifically deuterated. From C8 towards the methyl end the order and dynamics of the covalently attached acyl chains follow closely that of the phospholipids in a liquid crystalline bilayer. In contrast, the carboxyl part of the acyl chain is highly ordered and takes up a defined conformation. The results are discussed in the light of the structural and functional consequences of acylation of transmembrane proteins.