Peptide-binding specificity of the prosurfactant protein C Brichos domain analyzed by electrospray ionization mass spectrometry

Authors

  • Michael Fitzen,

    1. Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden
    2. Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, SE-751 23 Uppsala, Sweden
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  • Gunvor Alvelius,

    1. Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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  • Kerstin Nordling,

    1. Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, SE-751 23 Uppsala, Sweden
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  • Hans Jörnvall,

    1. Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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  • Tomas Bergman,

    Corresponding author
    1. Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden
    • Department of Medical Biochemistry and Biophysics, Division of Chemistry I, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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  • Jan Johansson

    1. Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, The Biomedical Centre, SE-751 23 Uppsala, Sweden
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Abstract

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. Copyright © 2009 John Wiley & Sons, Ltd.

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