Biomedical subjects

Rivka L Isaacson

Publications and source records attributed to Rivka L Isaacson.

2 recordsLinked to original sources

PubMed2006

Conformational changes in the AAA ATPase p97-p47 adaptor complex.

The AAA+ATPase p97/VCP, helped by adaptor proteins, exerts its essential role in cellular events such as endoplasmic reticulum-associated protein degradation or the reassembly of Golgi, ER and the nuclear envelope after mitosis. Here, we report the three-dimensional cryo-electron microscopy structures at approximately 20 Angstroms resolution in two nucleotide states of the endogenous hexameric p97 in complex with a recombinant p47 trimer, one of the major p97 adaptor proteins involved in membrane fusion. Depending on the nucleotide state, we observe the p47 trimer to be in two distinct arrangements on top of the p97 hexamer. By combining the EM data with NMR and other biophysical measurements, we propose a model of ATP-dependent p97(N) domain motions that lead to a rearrangement of p47 domains, which could result in the disassembly of target protein complexes.

Adenosine Triphosphatases↗

PubMed2002

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.

Amino Acid Substitution↗