4s3g

Publication Abstract from PubMed

Cation-pi interactions, where protein aromatic residues supply pi systems while positive charged portion of phospholipid head groups are the cations, have been suggested as important binding modes for peripheral membrane proteins. However, aromatic amino acids can also insert into membranes and hydrophobically interact with lipid tails. Heretofore there has been no facile way to differentiate these two types of interactions. We show that specific incorporation of fluorinated amino acids into proteins can experimentally distinguish cation-pi interactions from membrane insertion of the aromatic side-chains. Fluorinated aromatic amino acids destabilize the cation-pi interactions by altering electrostatics of the aromatic ring while their increased hydrophobicity enhances membrane insertion. Incorporation of pentafluorophenylalanine or difluorotyrosine into a Staphylococcus aureus phosphatidylinositol-specific phospholipase C (PI-PLC) variant engineered to contain a specific PC-binding site demonstrates the effectiveness of this methodology. Applying this methodology to the plethora of tyrosine residues in Bacillus thuringiensis PI-PLC definitively identifies those involved in cation-pi interactions with PC. This powerful method can easily be used to determine the roles of aromatic residues in other peripheral membrane proteins and in integral membrane proteins.

Fluorinated aromatic amino acids distinguish cation-pi interactions from membrane insertion.,He T, Gershenson A, Eyles SJ, Lee YJ, Liu WR, Wang J, Gao J, Roberts MF J Biol Chem. 2015 Jun 19. pii: jbc.M115.668343. PMID:26092728^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.