Hormone affinity and fibril formation of piscine transthyretin: the role of the N-terminal

Morgado, Isabel; Melo, Eduardo P.; Lundberg, Erik; Estrela, Nídia L.; Sauer-Eriksson, A. Elisabeth; Power, Deborah

http://hdl.handle.net/10400.1/5419

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Authors

Sauer-Eriksson, A. Elisabeth

Power, Deborah

Abstract(s)

Transthyretin (TTR) transports thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3) in the blood of vertebrates. TH-binding sites are highly conserved in vertebrate TTR however, piscine TTR has a longer N-terminus which is thought to influence TH-binding affinity and may influence TTR stability. We produced recombinant wild-type sea bream TTR (sbTTRWT) plus two mutants in which six (sbTTRM6) and twelve (sbTTRM12) N-terminal residues were removed. Ligandbinding studies revealed similar affinities for T3 (Kd=10.6±1.7nM) and T4 (Kd=9.8±0.97nM) binding to sbTTRWT. Affinity for THs was unaltered in sbTTRM12 but sbTTRM6 had poorer affinity for T4 (Kd=252.3±15.8nM) implying that some residues in the N-terminus can influence T4 binding. sbTTRM6 inhibited acid-mediated fibril formation in vitro as shown by fluorometric measurements using thioflavine-T.In contrast, fibril formation by sbTTRM12 was significant, probably due to decreased stability of the tetramer. Such studies also suggested that sbTTRWT is more resistant to fibril formation than human TTR.

Keywords

Amyloid fibrils Recombinant protein Ligand binding characteristics Transthyretin TTR tetramer stability

URI

http://hdl.handle.net/10400.1/5419

Citation

Isabel Morgado, Eduardo P. Melo, Erik Lundberg, N´ıdia L. Estrela, A. Elisabeth Sauer-Eriksson, Deborah M. Power, "Hormone affinity and fibril formation of piscine transthyretin The role of the N-terminal" in Molecular and Cellular Endocrinology 295, 1-2 (2008) 48.