Bacteriophage M13 major coat protein, roles of aromatic residues at the membrane-water interface

grantor: University of TorontoMajor coat protein of bacteriophage M13 was used as a model to study the roles of aromatic residues at the membrane-water interface of integral membrane proteins. Viable bacteriophages with either one of the interfacial tyrosine residues of the major coat protein mutated were generated, but no mutant with both tyrosine residues substituted was found, indicating a critical role for those residues when the protein is in the virion and/or in the membrane. Biophysical analyses indicated that mutants with a hydrophilic amino acid substitution are less buried in the interior of deoxycholate micelle. Such mutants also exhibit decreased protein-lipid interaction with the micelle, resulting in less difficulty for the protein to escape from the micelle and thus a lower Ã-helix to ß-sheet transition temperature. The results suggest that the interfacial aromatic residues are important in both the positioning and anchoring of the transmembrane segments of membrane proteins in the lipid bilayer.M.Sc