Naslov
NMR insights into predisposition for structural conversion of inherited human prion diseases

Autori
Plavec, Janez ; Ilc, Gregor ; Giachin, Gabriele ; Biljan, Ivana ; Legname, Giuseppe

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Prion, Volume 8, Supplement 1 / - : Landes Bioscience, 2014, 20-20

Skup
Prion 2014

Mjesto i datum
Trst, Italija, 27.05.2014. - 30.05.2014

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Prion protein; Mutants; NMR spectroscopy

Sažetak
NMR spectroscopy allows to obtain topological assignment and detailed atomic-level structure information. In human genetic forms of prion diseases, mutations in the C-terminal globular domain of PrPC (HuPrP) are hypothesized to favor spontaneous generation of PrPSc in the brain leading to neurodegeneration. High-resolution solution-state NMR structures on HuPrPs with Q212P and V210I mutations (linked to GSS and fCJD respectively) and HuPrP carrying the E219K polymorphism considered to protect against sCJD might provide insights into the early stages of prion conversion. Sequence-specific backbone and side-chain assignments were achieved to a very high degree enabling structure determination of mutant PrPs. Hundred twenty out of 141 residues were assigned, corresponding to 85% of the HuPrP sequence. Unassigned residues are mostly located around Phe175 and constitute a flexible segment of HuPrP structure. For those residues, the signals from NH protons are not observed in 1H, 15N-HSQC spectrum due to fast exchange with water. This part is involved in a pronounced chemical exchange process at the intermediate NMR timescale, resulting in an additional increase of resonance linewidths. The NMR structure of HuPrP carrying the Q212P mutation provides new insights into the early stages of spontaneous PrPC conversion into PrPSc. The secondary structure of the Q212P mutant consists of a flexible disordered tail (residues 90-124) and a globular domain (residues 125-231). The substitution of a proline at position 212 introduces unique structural differences in comparison to the known mammalian PrP structures, which are likely to have implications for understanding why and how changes in the native PrPC fold lead to neurodegeneration. Subtle local structural changes include an altered conformation of the β2-α2 loop along with loosening of tertiary contacts between the loop and the C-terminal end of helix α3, higher exposure of hydrophobic residues to solvent and perturbation of hydrophobic contacts at the α2-α3 inter-helical interface. Similar findings were found in the V210I mutant. However, hydrophobic interactions between residues from the β2-α2 loop and helix α3 are not interrupted in HuPrP with E219K polymorphism. In conclusion, our findings on disease-associated mutants and on E219K polymorphism provide new clues on the possible early events of HuPrP misfolding. The structural disorder of the β2-α2 loop, together with the increased distance between this loop and helix α3, observed in different mutants, lead to exposure of hydrophobic residues to solvent, thus facilitating intermolecular interactions with other PrP or with yet unknown cellular factors and abnormal accumulation inside the cells.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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