A new isoleucine substitution of Val-20 in transthyretin tetramers selectively impairs dimer-dimer contacts and causes systemic amyloidosis
| Autor: | Reinhold P. Linke, Klaus Denzel, Pia Winter, Dieter E. Jenne, Klaus Altland, Petra Blatzinger, Brigitte Obermaier |
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| Rok vydání: | 1996 |
| Předmět: |
Male
endocrine system Dimer Molecular Sequence Data chemistry.chemical_compound Biopolymers Tetramer medicine Humans Prealbumin Amino Acid Sequence Isoleucine Peptide sequence chemistry.chemical_classification Multidisciplinary Base Sequence biology Genetic Carrier Screening Amyloidosis nutritional and metabolic diseases Valine Middle Aged medicine.disease Pedigree Amino acid Transthyretin chemistry Biochemistry Mutation biology.protein Female Amyloid cardiomyopathy Research Article |
| Zdroj: | Proceedings of the National Academy of Sciences. 93:6302-6307 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | The most frequent form of inherited amyloidoses is associated with mutations in the transthyretin (TTR) gene coding for 127-amino acid residues of four identical, noncovalently linked subunits that form a pair of dimers in the plasma protein complex. Amyloid fibrils containing the variant and to a lesser extent the wild-type form of the TTR molecule are deposited in various organs, including peripheral nerves and the myocardium, with polyneuropathy and cardiomyopathy as major clinical manifestations. So far, more than 40 distinct amino acid substitutions distributed throughout the TTR sequence over 30 positions have been found to be correlated with an increased amyloidogenicity of TTR. Most of these amyloidogenic amino acid substitutions are suspected to alter the conformation and stability of the monomer. Here we identify and characterize by protein and DNA analysis a novel amyloidogenic Val-20 to Ile mutation in a German three-generation family. The index patient suffered from severe amyloid cardiomyopathy at the age of 60. Conformational stability and unfolding behavior of the Ile-20 monomer in urea gradients was found to be almost indistinguishable from that of wild-type TTR. In contrast, tetramer stability was significantly reduced in agreement with the expected change in the interactions between the two opposing dimers via the side chain of Ile-20. Our observations provide strong evidence for the view that amyloidogenic amino acid substitutions in TTR facilitate the conversion of tetrameric TTR complexes into those conformational intermediates of the TTR folding pathway that have an intrinsic amyloidogenic potential. |
| Databáze: | OpenAIRE |
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