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Cavity filling mutations at the thyroxine-binding site dramatically increase transthyretin stability and prevent its aggregation

2017; Nature Portfolio; Volume: 7; Issue: 1 Linguagem: Inglês

10.1038/srep44709

2045-2322

Ricardo Sant’Anna, Maria Rosário Almeida, Nathalia Varejão, Pablo Gallego, Sebastián Esperante, Priscila S. Ferreira, Alda Pereira-Henriques, Fernando L. Palhano, Mamede de Carvalho, Débora Foguel, David Reverter, Maria João Saraiva, Salvador Ventura,

Trace Elements in Health

More than a hundred different Transthyretin (TTR) mutations are associated with fatal systemic amyloidoses. They destabilize the protein tetrameric structure and promote the extracellular deposition of TTR as pathological amyloid fibrils. So far, only mutations R104H and T119M have been shown to stabilize significantly TTR, acting as disease suppressors. We describe a novel A108V non-pathogenic mutation found in a Portuguese subject. This variant is more stable than wild type TTR both in vitro and in human plasma, a feature that prevents its aggregation. The crystal structure of A108V reveals that this stabilization comes from novel intra and inter subunit contacts involving the thyroxine (T4) binding site. Exploiting this observation, we engineered a A108I mutation that fills the T4 binding cavity, as evidenced in the crystal structure. This synthetic protein becomes one of the most stable TTR variants described so far, with potential application in gene and protein replacement therapies.