| 1. |
- Groenning, Minna, et al.
(författare)
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Considerably Unfolded Transthyretin Monomers Preceed and Exchange with Dynamically Structured Amyloid Protofibrils
- 2015
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Ingår i: Scientific Reports. - : Nature Publishing Group: Open Access Journals - Option C / Nature Publishing Group. - 2045-2322. ; 5:11443
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Tidskriftsartikel (refereegranskat)abstract
- Despite numerous studies, a detailed description of the transthyretin (TTR) self-assembly mechanism and fibril structure in TTR amyloidoses remains unresolved. Here, using a combination of primarily small -angle X-ray scattering (SAXS) and hydrogen exchange mass spectrometry (HXMS) analysis, we describe an unexpectedly dynamic TTR protofibril structure which exchanges protomers with highly unfolded monomers in solution. The protofibrils only grow to an approximate final size of 2,900 kDa and a length of 70 nm and a comparative HXMS analysis of native and aggregated samples revealed a much higher average solvent exposure of TTR upon fibrillation. With SAXS, we reveal the continuous presence of a considerably unfolded TTR monomer throughout the fibrillation process, and show that a considerable fraction of the fibrillating protein remains in solution even at a late maturation state. Together, these data reveal that the fibrillar state interchanges with the solution state. Accordingly, we suggest that TTR fibrillation proceeds via addition of considerably unfolded monomers, and the continuous presence of amyloidogenic structures near the protofibril surface offers a plausible explanation for secondary nucleation. We argue that the presence of such dynamic structural equilibria must impact future therapeutic development strategies.
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| 2. |
- Groenning, Minna, et al.
(författare)
-
Thermodynamic stability and denaturation kinetics of a benign natural transthyretin mutant identified in a Danish kindred
- 2011
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Ingår i: AMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. - : Informa Healthcare. - 1350-6129. ; 18:2, s. 35-46
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Tidskriftsartikel (refereegranskat)abstract
- The disease phenotype of transthyretin (TTR) is dramatically influenced by single point mutations in the TTR gene. Herein, we report on a novel mutation D99N (Asp99Asn) in TTR found in a Danish kindred. None of the family members carrying this mutation have so far shown any clinical signs of amyloidosis. One carrier found compound heterozygous for TTR D99N and L111M (Leu111Met) associated with cardiac amyloid is asymptomatic (42 years). Disease severity can often be linked to both the kinetics of fibril formation and the degree of destabilisation of the native state. In this study, we show that the thermodynamic stability and rate of tetramer dissociation of the variant TTR D99N is unchanged or slightly more stable than wild type (WT) TTR. Furthermore, the in vitro fibrillation kinetics of the variant reveals an unchanged or slightly suppressed tendency to form fibrils compared to WT. Thus, the in vitro experiments support the lack of clinical symptoms observed so far for the TTR D99N carriers. In line with this, studies on kinetic stability and fibrillation kinetics reveal indistinguishable stability of TTR heterotetramers D99N/L111M compared to the heterotetramers WT/L111M. In conclusion, TTR D99N is predicted to be a non-pathogenic benign mutation with WT properties.andlt;/.
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