Loss of a metal-binding site in gelsolin leads to familial amyloidosis-Finnish type.
Mutations in domain 2 (D2, residues 151-266) of the actin-binding protein gelsolin cause familial amyloidosis-Finnish type (FAF). These mutations, D187N or D187Y, lead to abnormal proteolysis of plasma gelsolin at residues 172-173 and a second hydrolysis at residue 243, resulting in an amyloidogenic fragment. Here we present the structure of human gelsolin D2 at 1.65 A and find that Asp 187 is part of a Cd2+ metal-binding site. Two Ca2+ ions are required for a conformational transition of gelsolin to its active form. Differential scanning calorimetry (DSC) and molecular dynamics (MD) simulations suggest that the Cd2+-binding site in D2 is one of these two Ca2+-binding sites and is essential to the stability of D2. Mutation of Asp 187 to Asn disrupts Ca2+ binding in D2, leading to instabilities upon Ca2+ activation. These instabilities make the domain a target for aberrant proteolysis, thereby enacting the first step in the cascade leading to FAF.
Kazmirski
Steven L
SL
Cambridge University Chemical Laboratory and Cambridge Centre for Protein Engineering, MRC Centre, Hills Road, Cambridge CB2 2QH, UK.
Isaacson
Rivka L
RL
An
Chahm
C
Buckle
Ashley
A
Johnson
Christopher M
CM
Daggett
Valerie
V
Fersht
Alan R
AR
D019943:Amino Acid Substitution / Q000235:genetics; D028226:Amyloidosis, Familial / Q000235:genetics*; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D005387:Finland; D018260:Gelsolin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D018260:Gelsolin; D002104:Cadmium; D001224:Aspartic Acid; D002118:Calcium