Search for intermediate structures in transthyretin fibrillogenesis: soluble tetrameric Tyr78Phe TTR expresses a specific epitope present only in amyloid fibrils.

Familial Amyloidotic Polyneuropathy (FAP) is caused by the assembly of TTR into an insoluble beta-sheet. The TTR tetramer is thought to dissociate into monomeric intermediates and subsequently polymerise into the pathogenic amyloid form. The biochemical mechanism behind this transformation is unknown. We characterised intermediate TTR structures in the in vitro amyloidogenesis pathway by destabilising the AB loop through substitution of residue 78. Changes at this residue, should destabilise the TTR tetrameric fold, based on the known crystallographic structure of a Leu55Pro transthyretin variant. We generated a soluble tetrameric form of TTR that is recognised by a monoclonal antibody, previously reported to react only with highly amyloidogenic mutant proteins lacking the tetrameric native fold and with amyloid fibrils. BIAcore system analysis showed that Tyr78Phe had similar binding properties as synthetic fibrils. The affinity of this interaction was 10(7) M(-1). We suggest that the tetrameric structure of Tyr78Phe is altered due to the loosening of the AB loops of the tetramer, leading to a structure that might represent an early intermediate in the fibrillogenesis pathway.

[1]  S. Richardson,et al.  The evolution of gene expression, structure and function of transthyretin. , 1997, Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology.

[2]  S J Oatley,et al.  Structure of prealbumin: secondary, tertiary and quaternary interactions determined by Fourier refinement at 1.8 A. , 1977, Journal of molecular biology.

[3]  D. Kirschner,et al.  Analysis of x-ray diffraction patterns from amyloid of biopsied vitreous humor and kidney of transthyretin (TTR) Met30 familial amyloidotic polyneuropathy (FAP) patients: axially arrayed TTR monomers constitute the protofilament. , 1998, Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis.

[4]  D. Craik,et al.  1H-NMR structural studies of a cystine-linked peptide containing residues 71-93 of transthyretin and effects of a Ser84 substitution implicated in familial amyloidotic polyneuropathy. , 1999, European journal of biochemistry.

[5]  I. Dacklin,et al.  Characterization of two highly amyloidogenic mutants of transthyretin. , 1997, Biochemistry.

[6]  J. Palha,et al.  Antibody recognition of amyloidogenic transthyretin variants in serum of patients with familial amyloidotic polyneuropathy , 2002, Journal of Molecular Medicine.

[7]  C. Andrade,et al.  Familial amyloid polyneuropathy: an electron microscope study of the peripheral nerve in five cases. I. Interstitial changes. , 1971, Brain : a journal of neurology.

[8]  M. Saraiva,et al.  Designing transthyretin mutants affecting tetrameric structure: implications in amyloidogenicity. , 2000, The Biochemical journal.

[9]  M. Lawrence,et al.  Isolation, characterization, cDNA cloning and gene expression of an avian transthyretin. Implications for the evolution of structure and function of transthyretin in vertebrates. , 1991, European journal of biochemistry.

[10]  J. Kelly,et al.  The acid-mediated denaturation pathway of transthyretin yields a conformational intermediate that can self-assemble into amyloid. , 1996, Biochemistry.

[11]  A. Sousa,et al.  Compound heterozygotes of transthyretin Met30 and transthyretin Met119 are protected from the devastating effects of familial amyloid polyneuropathy , 1996, Neuromuscular Disorders.

[12]  M. Saraiva,et al.  Comparative stability and clearance of [Met30]transthyretin and [Met119]transthyretin. , 1997, European journal of biochemistry.

[13]  P. Lansbury,et al.  A chemical approach to elucidate tin mechanism of transthyretin and β-protein amyloid fibril formation , 1994 .

[14]  Y. Sakaki,et al.  'In vitro' amyloid fibril formation from transthyretin: the influence of ions and the amyloidogenicity of TTR variants. , 1996, Biochimica et biophysica acta.

[15]  Bo Johnsson,et al.  A novel hydrogel matrix on gold surfaces in surface plasmon resonance sensors for fast and efficient covalent immobilization of ligands , 1990 .

[16]  Y. Sakaki,et al.  Production of recombinant human transthyretin with biological activities toward the understanding of the molecular basis of familial amyloidotic polyneuropathy (FAP). , 1991, Biochemistry.

[17]  M. Saraiva,et al.  Exposure of cryptic epitopes on transthyretin only in amyloid and in amyloidogenic mutants. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[18]  P. Westermark,et al.  Mechanisms of transthyretin amyloidogenesis. Antigenic mapping of transthyretin purified from plasma and amyloid fibrils and within in situ tissue localizations. , 1994, The American journal of pathology.

[19]  D. Goodman,et al.  Transthyretin (prealbumin) in familial amyloidotic polyneuropathy: genetic and functional aspects. , 1988, Advances in neurology.

[20]  M. Saraiva,et al.  The Crystal Structure of Amyloidogenic Leu55→ Pro Transthyretin Variant Reveals a Possible Pathway for Transthyretin Polymerization into Amyloid Fibrils* , 1998, The Journal of Biological Chemistry.