Inhibitory interaction of a Porphyrin derivative with the protein α-synuclein

GARRO, HUGO A.; GENTILE, IÑAKI; RAMUNNO, CARLA F.; GONZALEZ, NAZARENO; DELGADO OCAÑA, SUSANA; GRIESINGER, CHRISTIAN; FERNÁNDEZ, CLAUDIO O.

Gottingen

Simposio; 16th HORIZONS IN MOLECULAR BIOLOGY; 2019

Max Planck Society

The misfolding of proteins into a toxic conformation and their deposition as amyloid-likefibrils are proposed to be at the molecular foundation of a number of neurodegenerative disordersincluding Creutzfeldt-Jakob, Alzheimer, and Parkinson diseases. A detailed understanding of themechanism by which proteins of wide structural diversity are transformed into morphologicallysimilar aggregates is therefore of high clinical importance.Alpha-synuclein (aS) aggregation is linked to the development of Parkinson?s disease. Structurally,aS contains 140 aminoacids distributed in three different regions. The use of aggregationinhibitors as molecular probes of the structural and toxic mechanisms related to amyloid formationis an active area of research.In the present study we applied a vast array of biophysical tools to investigate the binding andanti-amyloid properties of the small molecule Porphine (PfTS-3) on the amyloid fibril assembly ofthe protein aS. Moreover, a comparative analysis with the molecule Phthalocyanine tetrasulfonate(PcTS) was performed.We recorded NMR spectra on a spectrometer equipped with a cryogenically cooled tripleresonance 1H(13C/15N) TCI probe. 2D 1H-15N and 1H-13C HSQC experiments were used to mapthe interaction between aS (25, 50, 100 μM) and the small molecules at a residue specific level ofresolution. 1D 1H NMR experiments were used to monitor the monomer consumption duringthe progression of the aS (25, 50, 100 μM) aggregation process in the absence and presence of thestudied compounds.The results presented here allow us to conclude that: (i) PcTS and PfTS-3 compounds bind to themonomeric form of the protein aS; (ii) the N-terminal region of aS represents the binding interfacefor these compounds, mainly driven by aromatic and electrostatic interactions; (iii) Tyr at position39 and Phe at position 4 constitute the most affected residues by PcTS binding, whereas no suchspecific interactions were observed with the PfTS-3 compound; (iv) formation of the aS-PcTS andaS-PfTS-3 complexes affect the amyloid fibril assembly of the protein in different ways; (v) thedifferences observed in binding capacity and anti-amyloid activity of PcTS and PfTS-3 compoundson aS might be attributed to their distinct ability to self-stack through π-π interactions; (vi) thestructural and molecular mechanism behind the inhibitory effects of these compounds on aSamyloid fibril assembly are well different.