Phenylalanine assembly into toxic fibrils suggests amyloid etiology in phenylketonuria


Phenylketonuria (PKU) is characterized by phenylalanine accumulation and progressive mental retardation caused by an unknown mechanism. We demonstrate that at pathological concentrations, phenylalanine self-assembles into fibrils with amyloid-like morphology and well-ordered electron diffraction. These assemblies are specifically recognized by antibodies, show cytotoxicity that can be neutralized by the antibodies and are present in the hippocampus of model mice and in parietal cortex brain tissue from individuals with PKU. This is, to our knowledge, the first demonstration that a single amino acid can form amyloid-like deposits, suggesting a new amyloidosis-like etiology for PKU.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The single aromatic amino acid, phenylalanine, self-assembles into supramolecular fibrillar structures.
Figure 2: Specific antibodies against phenylalanine fibrils and the toxic effect and interaction of phenylalanine fibrillar structures with cell cultures.
Figure 3: Dot-blot analysis and histological staining indicates the presence of phenylalanine fibrils in model mice and PKU patient brain tissues.


  1. 1

    Hanley, W.B. Adult phenylketonuria. Am. J. Med. 117, 590–595 (2004).

    CAS  Article  Google Scholar 

  2. 2

    Surtees, R. & Blau, N. The neurochemistry of phenylketonuria. Eur. J. Pediatr. 159 (suppl.), S109–S113 (2000).

    CAS  Article  Google Scholar 

  3. 3

    Choi, T.B. & Pardridge, W.M. Phenylalanine transport at the human blood-brain barrier. Studies with isolated human brain capillaries. J. Biol. Chem. 261, 6536–6541 (1986).

    CAS  PubMed  Google Scholar 

  4. 4

    Krause, W. et al. Biochemical and neuropsychological effects of elevated plasma phenylalanine in patients with treated phenylketonuria. A model for the study of phenylalanine and brain function in man. J. Clin. Invest. 75, 40–48 (1985).

    CAS  Article  Google Scholar 

  5. 5

    MacDonald, A., Gokmen-Ozel, H., van Rijn, M. & Burgard, P. The reality of dietary compliance in the management of phenylketonuria. J. Inherit. Metab. Dis. 33, 665–670 (2010).

    Article  Google Scholar 

  6. 6

    Chiti, F. & Dobson, C.M. Protein misfolding, functional amyloid, and human disease. Annu. Rev. Biochem. 75, 333–366 (2006).

    CAS  Article  Google Scholar 

  7. 7

    Rochet, J.C. & Lansbury, P.T. Amyloid fibrillogenesis: themes and variations. Curr. Opin. Struct. Biol. 10, 60–68 (2000).

    CAS  Article  Google Scholar 

  8. 8

    Inouye, H., Sharma, D., Goux, W.J. & Kirschner, D.A. Structure of core domain of fibril-forming PHF/Tau fragments. Biophys. J. 90, 1774–1789 (2006).

    CAS  Article  Google Scholar 

  9. 9

    Gazit, E. A possible role for π-stacking in the self-assembly of amyloid fibrils. FASEB J. 16, 77–83 (2002).

    CAS  Article  Google Scholar 

  10. 10

    Makin, O.S. & Serpell, L.C. Structures for amyloid fibrils. FEBS J. 272, 5950–5961 (2005).

    CAS  Article  Google Scholar 

  11. 11

    Gazit, E. Global analysis of tandem aromatic octapeptide repeats: the significance of the aromatic-glycine motif. Bioinformatics 18, 880–883 (2002).

    CAS  Article  Google Scholar 

  12. 12

    Reches, M., Porat, Y. & Gazit, E. Amyloid fibril formation by pentapeptide and tetrapeptide fragments of human calcitonin. J. Biol. Chem. 277, 35475–35480 (2002).

    CAS  Article  Google Scholar 

  13. 13

    Reches, M. & Gazit, E. Casting metal nanowires within discrete self-assembled peptide nanotubes. Science 300, 625–627 (2003).

    CAS  Article  Google Scholar 

  14. 14

    Tjernberg, L.O. et al. Arrest of β-amyloid fibril formation by a pentapeptide ligand. J. Biol. Chem. 271, 8545–8548 (1996).

    CAS  Article  Google Scholar 

  15. 15

    Soto, C. β-sheet breaker peptides inhibit fibrillogenesis in a rat brain model of amyloidosis: implications for Alzheimer's therapy. Nat. Med. 4, 822–826 (1998).

    CAS  Article  Google Scholar 

  16. 16

    Hörster, F. et al. Phenylalanine reduces synaptic density in mixed cortical cultures from mice. Pediatr. Res. 59, 544–548 (2006).

    Article  Google Scholar 

  17. 17

    Makin, O.S., Atkins, E., Sikorski, P., Johansson, J. & Serpell, L.C. Molecular basis for amyloid fibril formation and stability. Proc. Natl. Acad. Sci. USA 102, 315–320 (2005).

    CAS  Article  Google Scholar 

  18. 18

    Brooks, B.R. et al. CHARMM: the biomolecular simulation program. J. Comput. Chem. 30, 1545–1614 (2009).

    CAS  Article  Google Scholar 

  19. 19

    Haberthür, U. & Caflisch, A. FACTS: fast analytical continuum treatment of solvation. J. Comput. Chem. 29, 701–715 (2008).

    Article  Google Scholar 

  20. 20

    Lesné, S. et al. A specific amyloid-β protein assembly in the brain impairs memory. Nature 440, 352–357 (2006).

    Article  Google Scholar 

  21. 21

    Abramov, E. et al. Amyloid-β as a positive endogenous regulator of release probability at hippocampal synapses. Nat. Neurosci. 12, 1567–1576 (2009).

    CAS  Article  Google Scholar 

  22. 22

    Shedlovsky, A., McDonald, J.D., Symula, D. & Dove, W.F. Mouse models of human phenylketonuria. Genetics 134, 1205–1210 (1993).

    CAS  PubMed  PubMed Central  Google Scholar 

  23. 23

    Gazit, V., Ben-Abraham, R., Pick, C.G. & Katz, Y. β-Phenylpyruvate induces long-term neurobehavioral damage and brain necrosis in neonatal mice. Behav. Brain Res. 143, 1–5 (2003).

    CAS  Article  Google Scholar 

  24. 24

    Cordero, M.E., Trejo, M., Colombo, M. & Aranda, V. Histological maturation of the neocortex in phenylketonuric rats. Early Hum. Dev. 8, 157–173 (1983).

    CAS  Article  Google Scholar 

  25. 25

    Lashuel, H.A., Hartley, D., Petre, B.M., Walz, T. & Lansbury, P.T. Neurodegenerative disease: amyloid pores from pathogenic mutations. Nature 418, 291 (2002).

    CAS  Article  Google Scholar 

  26. 26

    Bucciantini, M. et al. Inherent toxicity of aggregates implies a common mechanism for protein misfolding diseases. Nature 416, 507–511 (2002).

    CAS  Article  Google Scholar 

  27. 27

    Solomon, B. Clinical immunologic approaches for the treatment of Alzheimer's disease. Expert Opin. Investig. Drugs 16, 819–828 (2007).

    CAS  Article  Google Scholar 

  28. 28

    Schenk, D. et al. Immunization with amyloid-β attenuates Alzheimer-disease-like pathology in the PDAPP mouse. Nature 400, 173–177 (1999).

    CAS  Article  Google Scholar 

Download references


We thank R. Shaltiel-Karyo for confocal microscopy analysis, S. Wolf for the electron diffraction analysis, L. Buzhansky for help with the NMR and HPLC analysis, J. Delarea for help with TEM and SEM experiments, Z. Barkay for help with the SEM and ESEM analysis, S.-C. Jung (Ewha Womans University, Korea) for BTBR-Pahenu2 mouse plasma and tissue samples, C. Troakes (London Neurodegenerative Diseases Brain Bank, King's College London and part of BrainNet Europe) and T. Arzberger (Centre for Neuropathology and Prion Research, München) for brain tissue samples, I. Benhar and members of the Gazit laboratory for helpful discussions. L.A.-A. gratefully acknowledges the support of the Colton Foundation. This work was partly supported by the Israel Science Foundation–Legacy Heritage Biomedical Science Partnership grant 862/09 and the Alzheimer's Association grant NIRG-11-205535 (to D.F.). The work in the A.C. group was supported by the Swiss National Science Foundation.

Author information




L.A.-A., O.C. and E.G. conceived and designed the experiments. L.A.-A. and L.V. planned and performed the experiments. D.T., L.V. and L.A.-A. designed and performed the mouse and human histology experiments. D.F. designed and coordinated the mice and human histology experiments. A.M. designed and performed the molecular dynamics simulations. A.C. designed and coordinated the molecular dynamics simulations. L.A.-A. and E.G. wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Ehud Gazit.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Text and Figures

Supplementary Methods and Supplementary Results (PDF 1842 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Adler-Abramovich, L., Vaks, L., Carny, O. et al. Phenylalanine assembly into toxic fibrils suggests amyloid etiology in phenylketonuria. Nat Chem Biol 8, 701–706 (2012).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing