Design of single-layer beta-sheets without a hydrophobic core

Nature. 2000 Jan 27;403(6768):456-60. doi: 10.1038/35000255.


The hydrophobic effect is the main thermodynamic driving force in the folding of water-soluble proteins. Exclusion of nonpolar moieties from aqueous solvent results in the formation of a hydrophobic core in a protein, which has been generally considered essential for specifying and stabilizing the folded structures of proteins. Outer surface protein A (OspA) from Borrelia burgdorferi contains a three-stranded beta-sheet segment which connects two globular domains. Although this single-layer beta-sheet segment is exposed to solvent on both faces and thus does not contain a hydrophobic core, the segment has a high conformational stability. Here we report the engineering of OspA variants that contain larger single-layer beta-sheets (comprising five and seven beta-strands) by duplicating a beta-hairpin unit within the beta-sheet. Nuclear magnetic resonance and small-angle X-ray scattering analyses reveal that these extended single-layer beta-sheets are formed as designed, and amide hydrogen-deuterium exchange and chemical denaturation show that they are stable. Thus, interactions within the beta-hairpin unit and those between adjacent units, which do not involve the formation of a hydrophobic core, are sufficient to specify and stabilize the single-layer beta-sheet structure. Our results provide an expanded view of protein folding, misfolding and design.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Surface / chemistry*
  • Antigens, Surface / genetics
  • Bacterial Outer Membrane Proteins / chemistry*
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Vaccines
  • Borrelia burgdorferi Group
  • Lipoproteins*
  • Magnetic Resonance Spectroscopy
  • Protein Denaturation
  • Protein Folding
  • Protein Structure, Secondary
  • Scattering, Radiation


  • Antigens, Surface
  • Bacterial Outer Membrane Proteins
  • Bacterial Vaccines
  • Lipoproteins
  • OspA protein