Nanobody interaction unveils structure, dynamics and proteotoxicity of the Finnish-type amyloidogenic gelsolin variant

Publication date: Available online 6 January 2019Source: Biochimica et Biophysica Acta (BBA) - Molecular Basis of DiseaseAuthor(s): Toni Giorgino, Davide Mattioni, Amal Hassan, Mario Milani, Eloise Mastrangelo, Alberto Barbiroli, Adriaan Verhelle, Jan Gettemans, Maria Monica Barzago, Luisa Diomede, Matteo de RosaAbstractAGel amyloidosis, formerly known as familial amyloidosis of the Finnish-type, is caused by pathological aggregation of proteolytic fragments of plasma gelsolin. So far, four mutations in the gelsolin gene have been reported as responsible for the disease. Although D187N is the first identified variant and the best characterized, its structure has been hitherto elusive. Exploiting a recently-developed nanobody targeting gelsolin, we were able to stabilize the G2 domain of the D187N protein and obtained, for the first time, its high-resolution crystal structure. In the nanobody-stabilized conformation, the main effect of the D187N substitution is the impairment of the calcium binding capability, leading to a destabilization of the C-terminal tail of G2. However, molecular dynamics simulations show that in the absence of the nanobody, D187N-mutated G2 further misfolds, ultimately exposing its hydrophobic core and the furin cleavage site. The nanobody's protective effect is based on the enhancement of the thermodynamic stability of different G2 mutants (D187N, G167R and N184K). In particular, the nanobody reduces the flexibility of dynamic stretches, and most nota...
Source: Biochimica et Biophysica Acta (BBA) Molecular Basis of Disease - Category: Molecular Biology Source Type: research