Peptide-binding specificity of the prosurfactant protein C Brichos domain analyzed by electrospray ionization mass spectrometry.
The C-terminal domain of lung surfactant protein C (CTC) precursor (proSP-C) is involved in folding of the transmembrane segment of proSP-C. CTC includes a Brichos domain with homologs in cancer- and dementia-associated proteins. Mutations in the Brichos domain cause misfolding of proSP-C and hence amyloid fibril formation in interstitial lung disease. Electrospray ionization mass spectrometry (ESI-MS) with collision-induced dissociation (CID) experiments was applied to study non-covalent interactions between human recombinant CTC or its Brichos domain, and SP-C analogs, homotripeptides and peptides designed to model amyloid fibril formation. The results show that the Brichos domain contains the peptide-binding function of CTC. In titration experiments, apparent dissociation constants (KD) were in the micromolar range where triple-valine showed the lowest KD and triple-tyrosine the highest. Non-hydrophobic peptides failed to form complexes with Brichos. CID revealed that complexes with aromatic peptide ligands are more stable in the gas phase than complexes with non-aromatic ligands. The Brichos domain was also shown to bind fibril-forming peptides containing aromatic/hydrophobic residues.
Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Michael
M
Fitzen
Gunvor
G
Alvelius
Kerstin
K
Nordling
Hans
H
Jörnvall
Tomas
T
Bergman
Jan
J
Johansson
D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D037721:Pulmonary Surfactant-Associated Protein C / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D010455:Peptides; D037721:Pulmonary Surfactant-Associated Protein C; D011994:Recombinant Proteins