Title
S-Homocysteinylation effects on transthyretin: worsening of cardiomyopathy onset
Author
Manuela Leri, Paola Rebuzzini, Anna Caselli, Simone Luti, Antonino Natalello, Sofia Giorgetti, Loredana Marches, Silvia Garagna, Massimo Stefani, Paolo Paoli, Monica Bucciantini
Year
2020
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
Abstract
L-Homocysteine (Hcy) is a non-proteinogenic α-amino acid synthesized from dietary methionine. In healthy humans, high Hcy levels are a risk factor for cardiovascular diseases, stroke and type 2 diabetes. A recent study reports that Hcy reacts with Cys10 of transthyretin (TTR), generating a stable covalent adduct. However, to date the effect of S-homocysteinylation on TTR conformational stability remains unknown. The effect of Hcy on the conformational properties of wt- and L55P-TTR were analysed using a set of biophysical techniques. The cytotoxicity of S-homocysteinylated L55P-TTR was also evaluated in the HL-1 cardiomyocyte cell line, while the effects of the assemblies on kinematic and dynamics properties of cardiac muscle cells were analysed in cardiomyocyte syncytia. We found that Hcy stabilizes tetrameric wt-TTR, while it destabilizes the tetrameric structure of the L55P mutant, promoting the accumulation of self-assembly-prone monomeric species. Our study demonstrated that S-homocysteinylation of the L55P-TTR mutant impairs protein stability, favouring the appearance of toxic monomers. Interestingly, S-homocysteinylation affected only mutant, not wt-TTR. Moreover, we also show that assemblies of S-homocysteinylated L55P-TTR impair cardiomyocytes functional parameters.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Biochemistry