title: De novo design of fibrils made of short alpha-helical coiled coil peptides.
abstract: BACKGROUND
  The alpha-helical coiled coil structures formed by 25-50 residues long peptides are recognized as one of Nature's favorite ways of creating an oligomerization motif. Known de novo designed and natural coiled coils use the lateral dimension for oligomerization but not the axial one. Previous attempts to design alpha-helical peptides with a potential for axial growth led to fibrous aggregates which have an unexpectedly big and irregular thickness. These facts encouraged us to design a coiled coil peptide which self-assembles into soluble oligomers with a fixed lateral dimension and whose alpha-helices associate in a staggered manner and trigger axial growth of the coiled coil. Designing the coiled coil with a large number of subunits, we also pursue the practical goal of obtaining a valuable scaffold for the construction of multivalent fusion proteins.
  
  
  RESULTS
  The designed 34-residue peptide self-assembles into long fibrils at slightly acid pH and into spherical aggregates at neutral pH. The fibrillogenesis is completely reversible upon pH change. The fibrils were characterized using circular dichroism spectroscopy, sedimentation diffusion, electron microscopy, differential scanning calorimetry and X-ray fiber diffraction. The peptide was deliberately engineered to adopt the structure of a five-stranded coiled coil rope with adjacent alpha-helices, staggered along the fibril axis. As shown experimentally, the most likely structure matches the predicted five-stranded arrangement.
  
  
  CONCLUSIONS
  The fact that the peptide assembles in an expected fibril arrangement demonstrates the credibility of our conception of design. The discovery of a short peptide with fibril-forming ability and stimulus-sensitive behavior opens new opportunities for a number of applications.
authors.affiliation: Institute of Protein Research, Russian Academy of Science, Pushchino, Moscow Region, Russia.
authors.forename: S A
authors.initials: SA
authors.lastname: Potekhin
authors.forename: T N
authors.initials: TN
authors.lastname: Melnik
authors.forename: V
authors.initials: V
authors.lastname: Popov
authors.forename: N F
authors.initials: NF
authors.lastname: Lanina
authors.forename: A A
authors.initials: AA
authors.lastname: Vazina
authors.forename: P
authors.initials: P
authors.lastname: Rigler
authors.forename: A S
authors.initials: AS
authors.lastname: Verdini
authors.forename: G
authors.initials: G
authors.lastname: Corradin
authors.forename: A V
authors.initials: AV
authors.lastname: Kajava
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D015195:Drug Design; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry; D017433:Protein Structure, Secondary; D014961:X-Ray Diffraction
chemical_list: D010455:Peptides