A Zn‐dependent structural transition of SOD1 modulates its ability to undergo phase separation

Abstract

The misfolding and mutation of Cu/Zn superoxide dismutase (SOD1) is commonly associated with amyotrophic lateral sclerosis (ALS). SOD1 can accumulate within stress granules (SGs), a type of membraneless organelle, which is believed to form via liquid–liquid phase separation (LLPS). Using wild‐type, metal‐deficient, and different ALS disease mutants of SOD1 and computer simulations, we report here that the absence of Zn leads to structural disorder within two loop regions of SOD1, triggering SOD1 LLPS and amyloid formation. The addition of exogenous Zn to either metal‐free SOD1 or to the severe ALS mutation I113T leads to the stabilization of the loops and impairs SOD1 LLPS and aggregation. Moreover, partial Zn‐mediated inhibition of LLPS was observed for another severe ALS mutant, G85R, which shows perturbed Zn‐binding. By contrast, the ALS mutant G37R, which shows reduced Cu‐binding, does not undergo LLPS. In addition, SOD1 condensates induced by Zn‐depletion exhibit greater cellular toxicity than aggregates formed by prolonged incubation under aggregating conditions. Overall, our work establishes a role for Zn‐dependent modulation of SOD1 conformation and LLPS properties that may contribute to amyloid formation.

Amyloid Beta Oligomers Accelerate ATP-Dependent Phase Separation of miRNA-Bound Ago2 to RNA Processing Bodiesin vitro

“…The FCS correlation curves were fit to the 3D Gaussian 1-component diffusion model, where the beam waists in the radial and axial dimensions were calibrated using a standard fluorescence dye (Rhodamine 6G, R6G) in water of known diffusion coefficient (2.8 × 10 -6 cm 2 /sec). The diffusion coefficient of different samples are measured by measuring the diffusion time (τ D ) and using the relation (44) : The hydrodynamic radii of each species were computed from their respective diffusion coefficients (D). The FCS data obtained was normalized to free dye following a previously published method (45).…”

“…cm 2 /sec). The diffusion coefficient of different samples are measured by measuring the diffusion time (𝜏 # ) and using the relation (44) :…”

Zinc finger domains bind low-complexity domain polymers

“…Transcription factors with ZnFs, such as KLF4, ZEB1 and ZEB2, not only regulate the specific expression of human genome in the brain 34 but also are involved in neural development and neurodegenerative diseases [35][36][37][38] . Proteins with ZnFs or zinc binding lesions have been suggested to be involved in phase separation [39][40][41] . Further elucidation of the function of ZnFs, including interaction with LC domains, may lead to an understanding of the pathology of neurodegenerative diseases and the invention of therapeutic methods.…”

GōMartini 3: From large conformational changes in proteins to environmental bias corrections

“…It has been proposed that protein aggregation 80 , aberrant pro-oxidant catalysis 83 and metal dyshomeostasis 84 may be involved in the pathogenic mechanism. The proposed pathogenic processes listed have in common that they have been linked to loss of Zn(II) ions from the holoprotein [85][86][87][88][89][90][91] . Surprisingly, only a subset of ALS-linked SOD1 mutations occur close to the metal site 92 , raising questions about the molecular mechanisms involved in Zn(II) loss.…”