title: Removing an interhelical salt bridge abolishes coiled-coil formation in a de novo designed peptide.
abstract: Alpha-helical coiled coils represent a common protein oligomerization motif that are mainly stabilized by hydrophobic interactions occurring along their coiled-coil interface, the so-called hydrophobic seam. We have recently de novo designed and optimized a series of two-heptad repeat long coiled-coil peptides which are further stabilized by a complex network of inter- and intrahelical salt bridges. Here we have extended the de novo design of such two heptad-repeat long peptides by removing the central and most important g-e' Arg to Glu (g-e'RE) ionic interhelical interaction and replacing these residues by alanine residues. The effect of the missing interhelical ionic interaction on coiled-coil formation and stability has been analyzed by CD spectroscopy, analytical ultracentrifugation, and X-ray crystallography. We show that the peptide, while being highly alpha-helical, is no longer able to form a parallel coiled-coil structure but rather assumes an octameric globular helical assembly devoid of any coiled-coil interactions.
authors.affiliation: M.E. Müller Institute for Structural Biology, University of Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Meier
authors.forename: Ariel
authors.initials: A
authors.lastname: Lustig
authors.forename: Ueli
authors.initials: U
authors.lastname: Aebi
authors.forename: Peter
authors.initials: P
authors.lastname: Burkhard
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D001703:Biophysics / Q000379:methods*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D018698:Glutamic Acid / Q000737:chemistry; D007477:Ions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012492:Salts / Q000737:chemistry*; D013696:Temperature; D014461:Ultracentrifugation
chemical_list: D007477:Ions; D010455:Peptides; D012492:Salts; D018698:Glutamic Acid; D001120:Arginine