Emulation of the structure of the Saposin protein fold by a lung surfactant peptide construct of surfactant Protein B

PLoS One. 2022 Nov 3;17(11):e0276787. doi: 10.1371/journal.pone.0276787. eCollection 2022.

Abstract

The three-dimensional structure of the synthetic lung Surfactant Protein B Peptide Super Mini-B was determined using an integrative experimental approach, including mass spectrometry and isotope enhanced Fourier-transform infrared (FTIR) spectroscopy. Mass spectral analysis of the peptide, oxidized by solvent assisted region-specific disulfide formation, confirmed that the correct folding and disulfide pairing could be facilitated using two different oxidative structure-promoting solvent systems. Residue specific analysis by isotope enhanced FTIR indicated that the N-terminal and C-terminal domains have well defined α-helical amino acid sequences. Using these experimentally derived measures of distance constraints and disulfide connectivity, the ensemble was further refined with molecular dynamics to provide a medium resolution, residue-specific structure for the peptide construct in a simulated synthetic lung surfactant lipid multilayer environment. The disulfide connectivity combined with the α-helical elements stabilize the peptide conformationally to form a helical hairpin structure that resembles critical elements of the Saposin protein fold of the predicted full-length Surfactant Protein B structure.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Disulfides / chemistry
  • Lung / metabolism
  • Peptides
  • Protein Structure, Secondary
  • Pulmonary Surfactants* / metabolism
  • Saposins* / metabolism
  • Solvents
  • Spectroscopy, Fourier Transform Infrared
  • Surface-Active Agents

Substances

  • Saposins
  • IgA receptor
  • Pulmonary Surfactants
  • Peptides
  • Surface-Active Agents
  • Disulfides
  • Solvents