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. 1996 Aug;5(8):1662–1675. doi: 10.1002/pro.5560050820

Conformation and molecular topography of the N-terminal segment of surfactant protein B in structure-promoting environments.

L M Gordon 1, S Horvath 1, M L Longo 1, J A Zasadzinski 1, H W Taeusch 1, K Faull 1, C Leung 1, A J Waring 1
PMCID: PMC2143483  PMID: 8844855

Abstract

Although the effects of surfactant protein B (SP-B) on lipid surface activity in vitro and in vivo are well known, the relationship between molecular structure and function is still not fully understood. To further characterize protein structure-activity correlations, we have used physical techniques to study conformation, orientation, and molecular topography of N-terminal SP-B peptides in lipids and structure-promoting environments. Fourier transform infrared (FTIR) and CD measurements of SP-B1-25 (residues 1-25) in methanol, SDS micelles, egg yolk lecithin (EYL) liposomes, and surfactant lipids indicate the peptide has a dominant helical content, with minor turn and disordered components. Polarized FTIR studies of SP-B1-25 indicate the long molecular axis lies at an oblique angle to the surface of lipid films. Truncated peptides were similarly examined to assign more accurately the discrete conformations within the SP-B1-25 sequence. Residues Cys-8-Gly-25 are largely alpha-helix in methanol, whereas the N-terminal segment Phe-1-Cys-8 had turn and helical propensities. Addition of SP-B1-25 spin-labeled at the N-terminal Phe (i.e., SP-B1-25) to SDS, EYL, or surfactant lipids yielded electron spin resonance spectra that reflect peptide bound to lipids, but retaining considerable mobility. The absence of characteristic radical broadening indicates that SP-B1-25 is minimally aggregated when it interacts with these lipids. Further, the high polarity of SP-B1-25 argues that the reporter on Phe-1 resides in the headgroup of the lipid dispersions. The blue-shift in the endogenous fluorescence of Trp-9 near the N-terminus of SP-B1-25 suggests that this residue also lies near the lipid headgroup. A summary model based on the above physical experiments is presented for SP-B1-25 interacting with lipids.

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Selected References

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  1. Altenbach C., Hubbell W. L. The aggregation state of spin-labeled melittin in solution and bound to phospholipid membranes: evidence that membrane-bound melittin is monomeric. Proteins. 1988;3(4):230–242. doi: 10.1002/prot.340030404. [DOI] [PubMed] [Google Scholar]
  2. Baatz J. E., Elledge B., Whitsett J. A. Surfactant protein SP-B induces ordering at the surface of model membrane bilayers. Biochemistry. 1990 Jul 17;29(28):6714–6720. doi: 10.1021/bi00480a022. [DOI] [PubMed] [Google Scholar]
  3. Brauner J. W., Mendelsohn R., Prendergast F. G. Attenuated total reflectance Fourier transform infrared studies of the interaction of melittin, two fragments of melittin, and delta-hemolysin with phosphatidylcholines. Biochemistry. 1987 Dec 15;26(25):8151–8158. doi: 10.1021/bi00399a020. [DOI] [PubMed] [Google Scholar]
  4. Bruni R., Taeusch H. W., Waring A. J. Surfactant protein B: lipid interactions of synthetic peptides representing the amino-terminal amphipathic domain. Proc Natl Acad Sci U S A. 1991 Aug 15;88(16):7451–7455. doi: 10.1073/pnas.88.16.7451. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Byler D. M., Susi H. Examination of the secondary structure of proteins by deconvolved FTIR spectra. Biopolymers. 1986 Mar;25(3):469–487. doi: 10.1002/bip.360250307. [DOI] [PubMed] [Google Scholar]
  6. Curtain C. C., Looney F. D., Gordon L. M. Electron spin resonance spectroscopy in the study of lymphoid cell receptors. Methods Enzymol. 1987;150:418–446. doi: 10.1016/0076-6879(87)50098-2. [DOI] [PubMed] [Google Scholar]
  7. FOLCH J., LEES M., SLOANE STANLEY G. H. A simple method for the isolation and purification of total lipides from animal tissues. J Biol Chem. 1957 May;226(1):497–509. [PubMed] [Google Scholar]
  8. Fan B. R., Bruni R., Taeusch H. W., Findlay R., Waring A. J. Antibodies against synthetic amphipathic helical sequences of surfactant protein SP-B detect a conformational change in the native protein. FEBS Lett. 1991 May 6;282(2):220–224. doi: 10.1016/0014-5793(91)80481-h. [DOI] [PubMed] [Google Scholar]
  9. Fields C. G., Lloyd D. H., Macdonald R. L., Otteson K. M., Noble R. L. HBTU activation for automated Fmoc solid-phase peptide synthesis. Pept Res. 1991 Mar-Apr;4(2):95–101. [PubMed] [Google Scholar]
  10. Fiori W. R., Millhauser G. L. Exploring the peptide 3(10)-helix reversible alpha-helix equilibrium with double label electron spin resonance. Biopolymers. 1995;37(4):243–250. doi: 10.1002/bip.360370403. [DOI] [PubMed] [Google Scholar]
  11. Gaffney B. J., McNamee C. M. Spin-label measurements in membranes. With appendix: a use of computers in EPR spectroscopy. Methods Enzymol. 1974;32:161–198. [PubMed] [Google Scholar]
  12. Gill S. C., von Hippel P. H. Calculation of protein extinction coefficients from amino acid sequence data. Anal Biochem. 1989 Nov 1;182(2):319–326. doi: 10.1016/0003-2697(89)90602-7. [DOI] [PubMed] [Google Scholar]
  13. Goormaghtigh E., Cabiaux V., Ruysschaert J. M. Secondary structure and dosage of soluble and membrane proteins by attenuated total reflection Fourier-transform infrared spectroscopy on hydrated films. Eur J Biochem. 1990 Oct 24;193(2):409–420. doi: 10.1111/j.1432-1033.1990.tb19354.x. [DOI] [PubMed] [Google Scholar]
  14. Gordon L. M., Curtain C. C., Zhong Y. C., Kirkpatrick A., Mobley P. W., Waring A. J. The amino-terminal peptide of HIV-1 glycoprotein 41 interacts with human erythrocyte membranes: peptide conformation, orientation and aggregation. Biochim Biophys Acta. 1992 Aug 25;1139(4):257–274. doi: 10.1016/0925-4439(92)90099-9. [DOI] [PubMed] [Google Scholar]
  15. Gordon L. M., Looney F. D., Curtain C. C. Spin probe clustering in human erythrocyte ghosts. J Membr Biol. 1985;84(1):81–95. doi: 10.1007/BF01871650. [DOI] [PubMed] [Google Scholar]
  16. Griffith O. H., Dehlinger P. J., Van S. P. Shape of the hydrophobic barrier of phospholipid bilayers (evidence for water penetration in biological membranes). J Membr Biol. 1974;15(2):159–192. doi: 10.1007/BF01870086. [DOI] [PubMed] [Google Scholar]
  17. Hollósi M., Majer Z., Rónai A. Z., Magyar A., Medzihradszky K., Holly S., Perczel A., Fasman G. D. CD and Fourier transform ir spectroscopic studies of peptides. II. Detection of beta-turns in linear peptides. Biopolymers. 1994 Feb;34(2):177–185. doi: 10.1002/bip.360340204. [DOI] [PubMed] [Google Scholar]
  18. Hubbell W. L., McConnell H. M. Molecular motion in spin-labeled phospholipids and membranes. J Am Chem Soc. 1971 Jan 27;93(2):314–326. doi: 10.1021/ja00731a005. [DOI] [PubMed] [Google Scholar]
  19. Jacobs R. E., White S. H. The nature of the hydrophobic binding of small peptides at the bilayer interface: implications for the insertion of transbilayer helices. Biochemistry. 1989 Apr 18;28(8):3421–3437. doi: 10.1021/bi00434a042. [DOI] [PubMed] [Google Scholar]
  20. Johnson W. C., Jr Protein secondary structure and circular dichroism: a practical guide. Proteins. 1990;7(3):205–214. doi: 10.1002/prot.340070302. [DOI] [PubMed] [Google Scholar]
  21. Jones J. D., Gierasch L. M. Effect of charged residue substitutions on the membrane-interactive properties of signal sequences of the Escherichia coli LamB protein. Biophys J. 1994 Oct;67(4):1534–1545. doi: 10.1016/S0006-3495(94)80627-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Jost P. C., Griffith O. H. The spin-labeling technique. Methods Enzymol. 1978;49:369–418. doi: 10.1016/s0076-6879(78)49019-6. [DOI] [PubMed] [Google Scholar]
  23. Keith A., Horvat D., Snipes W. Spectral characterization of 15N spin labels. Chem Phys Lipids. 1974 Aug;13(1):49–62. doi: 10.1016/0009-3084(74)90041-3. [DOI] [PubMed] [Google Scholar]
  24. Longo M. L., Bisagno A. M., Zasadzinski J. A., Bruni R., Waring A. J. A function of lung surfactant protein SP-B. Science. 1993 Jul 23;261(5120):453–456. doi: 10.1126/science.8332910. [DOI] [PubMed] [Google Scholar]
  25. Longo M. L., Waring A., Zasadzinski J. A. Lipid bilayer surface association of lung surfactant protein SP-B, amphipathic segment detected by flow immunofluorescence. Biophys J. 1992 Sep;63(3):760–773. doi: 10.1016/S0006-3495(92)81643-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Matsuzaki K., Shioyama T., Okamura E., Umemura J., Takenaka T., Takaishi Y., Fujita T., Miyajima K. A comparative study on interactions of alpha-aminoisobutyric acid containing antibiotic peptides, trichopolyn I and hypelcin A with phosphatidylcholine bilayers. Biochim Biophys Acta. 1991 Dec 9;1070(2):419–428. doi: 10.1016/0005-2736(91)90082-j. [DOI] [PubMed] [Google Scholar]
  27. Mchaourab H. S., Hyde J. S., Feix J. B. Aggregation state of spin-labeled cecropin AD in solution. Biochemistry. 1993 Nov 9;32(44):11895–11902. doi: 10.1021/bi00095a019. [DOI] [PubMed] [Google Scholar]
  28. Miick S. M., Martinez G. V., Fiori W. R., Todd A. P., Millhauser G. L. Short alanine-based peptides may form 3(10)-helices and not alpha-helices in aqueous solution. Nature. 1992 Oct 15;359(6396):653–655. doi: 10.1038/359653a0. [DOI] [PubMed] [Google Scholar]
  29. Morrow M. R., Pérez-Gil J., Simatos G., Boland C., Stewart J., Absolom D., Sarin V., Keough K. M. Pulmonary surfactant-associated protein SP-B has little effect on acyl chains in dipalmitoylphosphatidylcholine dispersions. Biochemistry. 1993 Apr 27;32(16):4397–4402. doi: 10.1021/bi00067a032. [DOI] [PubMed] [Google Scholar]
  30. Okamura E., Umemura J., Takenaka T. Orientation studies of hydrated dipalmitoylphosphatidylcholine multibilayers by polarized FTIR-ATR spectroscopy. Biochim Biophys Acta. 1990 Jun 11;1025(1):94–98. doi: 10.1016/0005-2736(90)90195-t. [DOI] [PubMed] [Google Scholar]
  31. Oosterlaken-Dijksterhuis M. A., Haagsman H. P., van Golde L. M., Demel R. A. Characterization of lipid insertion into monomolecular layers mediated by lung surfactant proteins SP-B and SP-C. Biochemistry. 1991 Nov 12;30(45):10965–10971. doi: 10.1021/bi00109a022. [DOI] [PubMed] [Google Scholar]
  32. Oosterlaken-Dijksterhuis M. A., van Eijk M., van Golde L. M., Haagsman H. P. Lipid mixing is mediated by the hydrophobic surfactant protein SP-B but not by SP-C. Biochim Biophys Acta. 1992 Sep 21;1110(1):45–50. doi: 10.1016/0005-2736(92)90292-t. [DOI] [PubMed] [Google Scholar]
  33. Perczel A., Hollósi M., Sándor P., Fasman G. D. The evaluation of type I and type II beta-turn mixtures. Circular dichroism, NMR and molecular dynamics studies. Int J Pept Protein Res. 1993 Mar;41(3):223–236. doi: 10.1111/j.1399-3011.1993.tb00330.x. [DOI] [PubMed] [Google Scholar]
  34. Possmayer F. A proposed nomenclature for pulmonary surfactant-associated proteins. Am Rev Respir Dis. 1988 Oct;138(4):990–998. doi: 10.1164/ajrccm/138.4.990. [DOI] [PubMed] [Google Scholar]
  35. Pérez-Gil J., Casals C., Marsh D. Interactions of hydrophobic lung surfactant proteins SP-B and SP-C with dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol bilayers studied by electron spin resonance spectroscopy. Biochemistry. 1995 Mar 28;34(12):3964–3971. doi: 10.1021/bi00012a014. [DOI] [PubMed] [Google Scholar]
  36. Pérez-Gil J., Cruz A., Casals C. Solubility of hydrophobic surfactant proteins in organic solvent/water mixtures. Structural studies on SP-B and SP-C in aqueous organic solvents and lipids. Biochim Biophys Acta. 1993 Jul 1;1168(3):261–270. doi: 10.1016/0005-2760(93)90181-8. [DOI] [PubMed] [Google Scholar]
  37. Sauerheber R. D., Gordon L. M., Crosland R. D., Kuwahara M. D. Spin-label studies on rat liver and heart plasma membranes: do probe-probe interactions interfere with the measurement of membrane properties? J Membr Biol. 1977 Feb 24;31(1-2):131–169. doi: 10.1007/BF01869402. [DOI] [PubMed] [Google Scholar]
  38. Seelig J., Hasselbach W. A spin label study of sarcoplasmic vesicles. Eur J Biochem. 1971 Jul 15;21(1):17–21. doi: 10.1111/j.1432-1033.1971.tb01434.x. [DOI] [PubMed] [Google Scholar]
  39. Takahashi A., Waring A. J., Amirkhanian J., Fan B., Taeusch H. W. Structure-function relationships of bovine pulmonary surfactant proteins: SP-B and SP-C. Biochim Biophys Acta. 1990 May 1;1044(1):43–49. doi: 10.1016/0005-2760(90)90216-k. [DOI] [PubMed] [Google Scholar]
  40. Vandenbussche G., Clercx A., Clercx M., Curstedt T., Johansson J., Jörnvall H., Ruysschaert J. M. Secondary structure and orientation of the surfactant protein SP-B in a lipid environment. A Fourier transform infrared spectroscopy study. Biochemistry. 1992 Sep 29;31(38):9169–9176. doi: 10.1021/bi00153a008. [DOI] [PubMed] [Google Scholar]
  41. Vincent J. S., Revak S. D., Cochrane C. D., Levin I. W. Interactions of model human pulmonary surfactants with a mixed phospholipid bilayer assembly: Raman spectroscopic studies. Biochemistry. 1993 Aug 17;32(32):8228–8238. doi: 10.1021/bi00083a025. [DOI] [PubMed] [Google Scholar]
  42. Vincent J. S., Revak S. D., Cochrane C. G., Levin I. W. Raman spectroscopic studies of model human pulmonary surfactant systems: phospholipid interactions with peptide paradigms for the surfactant protein SP-B. Biochemistry. 1991 Aug 27;30(34):8395–8401. doi: 10.1021/bi00098a017. [DOI] [PubMed] [Google Scholar]
  43. Waring A., Taeusch W., Bruni R., Amirkhanian J., Fan B., Stevens R., Young J. Synthetic amphipathic sequences of surfactant protein-B mimic several physicochemical and in vivo properties of native pulmonary surfactant proteins. Pept Res. 1989 Sep-Oct;2(5):308–313. [PubMed] [Google Scholar]

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