Improved Detection of Multi-phosphorylated Peptides by LC-MS/MS without Phosphopeptide Enrichment

  • Kim, Suwha (Department of Life Sciences, Gwangju Institute of Science and Technology) ;
  • Choi, Hyunwoo (Department of Life Sciences, Gwangju Institute of Science and Technology) ;
  • Park, Zee-Yong (Department of Life Sciences, Gwangju Institute of Science and Technology)
  • Received : 2007.01.12
  • Accepted : 2007.03.06
  • Published : 2007.06.30

Abstract

Although considerable effort has been devoted in the mass spectrometric analysis of phosphorylated peptides, successful identification of multi-phosphorylated peptides in enzymatically digested protein samples still remains challenging. The ionization behavior of multi-phosphorylated peptides appears to be somewhat different from that of mono- or di-phosphorylated peptides. In this study, we demonstrate increased sensitivity of detection of multi-phosphorylated peptides of beta casein without using phosphopeptide enrichment techniques. Proteinase K digestion alone increased the detection limit of beta casein multi-phosphorylated peptides in the LC-MS analysis almost 500 fold, compared to conventional trypsin digestion (~50 pmol). In order to understand this effect, various factors affecting the ionization of phosphopeptides were investigated. Unlike ionizations of phosphopeptides with minor modifications, those of multi-phosphorylated peptides appeared to be subject to effects such as selectively suppressed ionization by more ionizable peptides and decreased ionization efficiency by multi-phosphorylation. The enhanced detection limit of multi-phosphorylated peptides resulting from proteinase K digestion was validated using a complex protein sample, namely a lysate of HEK 293 cells. Compared to trypsin digestion, the numbers of phosphopeptides identified and modification sites per peptide were noticeably increased by proteinase K digestion. Non-specific proteases such as proteinase K and elastase have been used in the past to increase detection of phosphorylation sites but the effectiveness of proteinase K digestion for multi-phosphorylated peptides has not been reported.

Keywords

References

  1. Andersson, L. and Porath, J. (1986) Isolation of phosphoproteins by immobilized metal (Fe3+) affinity chromatography. Anal. Biochem. 154, 250-254 https://doi.org/10.1016/0003-2697(86)90523-3
  2. Annan, R. S., Huddleston, M. J., Verma, R., Deshaies, R. J., and Carr, S. A. (2001) A multidimensional electrospray MS-based approach to phosphopeptide mapping. Anal. Chem. 73, 393-404 https://doi.org/10.1021/ac001130t
  3. Ballif, B. A., Villen, J., Beausoleil, S. A., Schwartz, D., and Gygi, S. P. (2004) Phosphoproteomic analysis of the developing mouse brain. Mol. Cell. Proteomics 3, 1093-1101 https://doi.org/10.1074/mcp.M400085-MCP200
  4. Beausoleil, S. A., Jedrychowski, M., Schwartz, D., Elias, J. E., Villen, J., et al. (2004) Large-scale characterization of HeLa cell nuclear phosphoproteins. Proc. Natl. Acad. Sci. USA 101, 12130-12135
  5. Blagoev, B., Ong, S. E., Kratchmarova, I., and Mann, M. (2004) Temporal analysis of phosphotyrosine-dependent signaling networks by quantitative proteomics. Nat. Biotechnol. 22, 1139-1145 https://doi.org/10.1038/nbt1005
  6. Ficarro, S. B., McCleland, M. L., Stukenberg, P. T., Burke, D. J., Ross, M. M., et al. (2002) Phosphoproteome analysis by mass spectrometry and its application to Saccharomyces cerevisiae. Nat. Biotechnol. 20, 301-305 https://doi.org/10.1038/nbt0302-301
  7. Garcia, B. A., Shabanowitz, J., and Hunt, D. F. (2005) Analysis of protein phosphorylation by mass spectrometry. Methods 35, 256-264 https://doi.org/10.1016/j.ymeth.2004.08.017
  8. Gerber, S. A., Rush, J., Stemman, O., Kirschner, M. W., and Gygi, S. P. (2003) Absolute quantification of proteins and phosphoproteins from cell lysates by tandem MS. Proc. Natl. Acad. Sci. USA 100, 6940-6945
  9. Goshe, M. B., Conrads, T. P., Panisko, E. A., Angell, N. H., Veenstra, T. D., et al. (2001) Phosphoprotein isotope-coded affinity tag approach for isolating and quantitating phosphopeptides in proteome-wide analyses. Anal. Chem. 73, 2578-2586 https://doi.org/10.1021/ac010081x
  10. Hunter, T. (1995) When is a lipid kinase not a lipid kinase? When it is a protein kinase. Cell 83, 1-4 https://doi.org/10.1016/0092-8674(95)90225-2
  11. Hunter, T. (2000) Signaling--2000 and beyond. Cell 100, 113-127 https://doi.org/10.1016/S0092-8674(00)81688-8
  12. Kim, J., Camp, D. G., 2nd, and Smith, R. D. (2004) Improved detection of multi-phosphorylated peptides in the presence of phosphoric acid in liquid chromatography/mass spectrometry. J. Mass Spectrom. 39, 208-215 https://doi.org/10.1002/jms.593
  13. Knight, Z. A., Schilling, B., Row, R. H., Kenski, D. M., Gibson, B. W., et al. (2003) Phosphospecific proteolysis for mapping sites of protein phosphorylation. Nat. Biotechnol. 21, 1047-1054 https://doi.org/10.1038/nbt863
  14. Koliakos, G., Trachana, V., Gaitatzi, M., and Dimitriadou, A. (2001) Phosphorylation of laminin-1 by protein kinase C. Mol. Cells 11, 179-185
  15. Li, W., Boykins, R. A., Backlund, P. S., Wang, G., and Chen, H. C. (2002) Identification of phosphoserine and phosphothreonine as cysteic acid and beta-methylcysteic acid residues in peptides by tandem mass spectrometric sequencing. Anal. Chem. 74, 5701-5710 https://doi.org/10.1021/ac020259v
  16. Liu, S., Zhang, C., Campbell, J. L., Zhang, H., Yeung, K. K., et al. (2005) Formation of phosphopeptide-metal ion complexes in liquid chromatography/electrospray mass spectrometry and their influence on phosphopeptide detection. Rapid Commun. Mass Spectrom. 19, 2747-2756 https://doi.org/10.1002/rcm.2105
  17. MacCoss, M. J., McDonald, W. H., Saraf, A., Sadygov, R., Clark, J. M., et al. (2002a) Shotgun identification of protein modifications from protein complexes and lens tissue. Proc. Natl. Acad. Sci. USA 99, 7900-7905
  18. MacCoss, M. J., Wu, C. C., and Yates, J. R., 3rd (2002b) Probability-based validation of protein identifications using a modified SEQUEST algorithm. Anal. Chem. 74, 5593-5599 https://doi.org/10.1021/ac025826t
  19. Mann, M., Ong, S. E., Gronborg, M., Steen, H., Jensen, O. N., et al. (2002) Analysis of protein phosphorylation using mass spectrometry: deciphering the phosphoproteome. Trends Biotechnol. 20, 261-268 https://doi.org/10.1016/S0167-7799(02)01944-3
  20. McLachlin, D. T. and Chait, B. T. (2001) Analysis of phosphorylated proteins and peptides by mass spectrometry. Curr. Opin. Chem. Biol. 5, 591-602 https://doi.org/10.1016/S1367-5931(00)00250-7
  21. McLachlin, D. T. and Chait, B. T. (2003) Improved betaelimination- based affinity purification strategy for enrichment of phosphopeptides. Anal. Chem. 75, 6826-6836 https://doi.org/10.1021/ac034989u
  22. Oda, Y., Nagasu, T., and Chait, B. T. (2001) Enrichment analysis of phosphorylated proteins as a tool for probing the phosphoproteome. Nat. Biotechnol. 19, 379-382 https://doi.org/10.1038/86783
  23. Olsen, J. V., Blagoev, B., Gnad, F., Macek, B., Kumar, C., et al. (2006) Global, in vivo, and site-specific phosphorylation dynamics in signaling networks. Cell 127, 635-648 https://doi.org/10.1016/j.cell.2006.09.026
  24. Pandey, A., Podtelejnikov, A. V., Blagoev, B., Bustelo, X. R., Mann, M., et al. (2000) Analysis of receptor signaling pathways by mass spectrometry: identification of vav-2 as a substrate of the epidermal and platelet-derived growth factor receptors. Proc. Natl. Acad. Sci. USA 97, 179-184
  25. Pinkse, M. W., Uitto, P. M., Hilhorst, M. J., Ooms, B., and Heck, A. J. (2004) Selective isolation at the femtomole level of phosphopeptides from proteolytic digests using 2D-NanoLCESI- MS/MS and titanium oxide precolumns. Anal. Chem. 76, 3935-3943 https://doi.org/10.1021/ac0498617
  26. Schlosser, A., Pipkorn, R., Bossemeyer, D., and Lehmann, W. D. (2001) Analysis of protein phosphorylation by a combination of elastase digestion and neutral loss tandem mass spectrometry. Anal. Chem. 73, 170-176 https://doi.org/10.1021/ac000826j
  27. Schlosser, A., Vanselow, J. T., and Kramer, A. (2005) Mapping of phosphorylation sites by a multi-protease approach with specific phosphopeptide enrichment and NanoLC-MS/MS analysis. Anal. Chem. 77, 5243-5250 https://doi.org/10.1021/ac050232m
  28. Steen, H., Jebanathirajah, J. A., Rush, J., Morrice, N., and Kirschner, M. W. (2006) Phosphorylation analysis by mass spectrometry: myths, facts, and the consequences for qualitative and quantitative measurements. Mol. Cell. Proteomics 5, 172-181 https://doi.org/10.1074/mcp.M500135-MCP200
  29. Vosseller, K., Hansen, K. C., Chalkley, R. J., Trinidad, J. C., Wells, L., et al. (2005) Quantitative analysis of both protein expression and serine / threo-nine post-translational modifications through stable isotope labeling with dithiothreitol. Proteomics 5, 388-398 https://doi.org/10.1002/pmic.200401066
  30. Yan, J. X., Packer, N. H., Gooley, A. A., and Williams, K. L. (1998) Protein phosphorylation: technologies for the identification of phosphoamino acids. J. Chromatogr. A 808, 23-41 https://doi.org/10.1016/S0021-9673(98)00115-0
  31. Zhang, H., Zhang, C., Lajoie, G. A., and Yeung, K. K. (2005) Selective sampling of phosphopeptides for detection by MALDI mass spectrometry. Anal. Chem. 77, 6078-6084 https://doi.org/10.1021/ac050565j
  32. Zhou, H., Watts, J. D., and Aebersold, R. (2001) A systematic approach to the analysis of protein phosphorylation. Nat. Biotechnol. 19, 375-378 https://doi.org/10.1038/86777