De novo design of a pentameric coiled-coil: decoding the motif for tetramer versus pentamer formation in water-soluble phospholamban

J Pept Res. 2005 Mar;65(3):312-21. doi: 10.1111/j.1399-3011.2005.00244.x.


Water-soluble phospholamban (WSPLB) is a designed, water-soluble analogue of the pentameric membrane protein phospholamban (PLB), which contains the same core and interhelical residues as PLB, with only the solvent-exposed positions mutated. WSPLB contains the same secondary and quaternary structure as PLB. The hydrophobic cores of PLB and WSPLB contain Leu and Ile at the a- and d-positions of a heptad repeat (abcdefg) from residues 31-52, while residues 21-30 are rich in polar amino acids at these positions. While the full-length WSPLB forms pentamers in solution, truncated peptides lacking residues 21-30 are largely tetrameric. Thus, truncation of residues 1-20 promotes a switch from pentamer to tetramer formation. Here, the motifs for WSPLB pentamerization were elucidated by characterizing a series of peptides, which were progressively truncated in this polar 'switch' region. When fully present, the 'switch' region promotes pentamer formation in WSPLB, by destabilizing a more stable tetrameric species which exists in its absence. We find that the burial of hydrogen bonding residues from 21 to 30 drives WSPLB from a tetramer to a pentamer, with direct implications for coiled-coil design.

MeSH terms

  • Amino Acid Motifs*
  • Calcium-Binding Proteins / chemistry*
  • Circular Dichroism
  • Models, Molecular
  • Peptide Fragments / chemistry
  • Protein Denaturation
  • Protein Engineering*
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Solubility
  • Water


  • Calcium-Binding Proteins
  • Peptide Fragments
  • phospholamban
  • Water