Dataset Information

Lamin A dimer and tetramer cross-links help explain disease mutations and polymer plasticity

ABSTRACT: Lamins are intermediate filament proteins responsible for nuclear mechanical integrity. Though linked to multiple heritable diseases, lamin structure and that of other intermediate filaments remains elusive. We employed cross-linking mass spectrometry to gain structural insights into lamin A dimer and tetramer structure. While confirming the parallel coiled-coil rod, we report that, contrary to prediction, rod linker regions are highly flexible and compressible. This explains the recently reported rod shortening in the assembled polymer and aspects of intermediate filament stretch properties. We further elucidate an extended interface in lamin A tetramers where both head and tail unstructured regions flanking the rod of each dimer act as polar bridges to stabilize lamin head-to-tail assembly. Furthermore, changes in these regions between dimer and tetramer forms suggest an ordered polymer assembly. Importantly, several residues mutated in laminopathies disrupt this interface and impair assembly, potentially explaining their role in disease.

INSTRUMENT(S): Orbitrap Fusion Lumos, LTQ Orbitrap Velos

ORGANISM(S): Rattus Norvegicus (rat) Homo Sapiens (human)

SUBMITTER: Juan Zou

LAB HEAD: Prof. Juri Rappsilber

PROVIDER: PXD008337 | Pride | 2019-07-12

REPOSITORIES: Pride

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Publications

Lamin A molecular compression and sliding as mechanisms behind nucleoskeleton elasticity.

Makarov Alex A AA Zou Juan J Houston Douglas R DR Spanos Christos C Solovyova Alexandra S AS Cardenal-Peralta Cristina C Rappsilber Juri J Schirmer Eric C EC

Nature communications 20190711 1

Lamin A is a nuclear intermediate filament protein critical for nuclear architecture and mechanics and mutated in a wide range of human diseases. Yet little is known about the molecular architecture of lamins and mechanisms of their assembly. Here we use SILAC cross-linking mass spectrometry to determine interactions within lamin dimers and between dimers in higher-order polymers. We find evidence for a compression mechanism where coiled coils in the lamin A rod can slide onto each other to cont ...[more]

PMID: 31296869

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Project description:Mutations in the gene encoding Cu-Zn superoxide dismutase 1 (SOD1) cause a subset of familial amyotrophic lateral sclerosis (fALS) cases. A shared effect of these mutations is that SOD1, which is normally a stable dimer, dissociates into toxic monomers that seed toxic aggregates. Considerable research effort has been devoted to developing compounds that stabilize the dimer of fALS SOD1 variants, but unfortunately, this has not yet resulted in a treatment. We hypothesized that cyclic thiosulfinate cross-linkers, which selectively target a rare, two cysteine-containing motif, can stabilize fALS-causing SOD1 variants in vivo. We created a library of chemically diverse cyclic thiosulfinates and determined structure-cross-linking-activity relationships. A pre-lead compound, “S-XL6,” was selected based upon its cross-linking rate and drug-like properties. Co-crystallographic structure clearly establishes the binding of S-XL6 at Cys 111 bridging the monomers and stabilizing the SOD1 dimer. Biophysical studies reveal that the degree of stabilization afforded by S-XL6 (up to 24 °C) is unprecedented for fALS, and to our knowledge, for any protein target of any kinetic stabilizer. Gene silencing and protein degrading therapeutic approaches require careful dose titration to balance the benefit of diminished fALS SOD1 expression with the toxic loss-of enzymatic function. We show that S-XL6 does not share this liability because it rescues the activity of fALS SOD1 variants. No pharmacological agent has been proven to bind to SOD1 in vivo. Here, using a fALS mouse model, we demonstrate oral bioavailability; rapid engagement of SOD1G93A by S-XL6 that increases SOD1G93A’s in vivo half-life; and that S-XL6 crosses the blood-brain barrier. S-XL6 demonstrated a degree of selectivity by avoiding off-target binding to plasma proteins. Taken together, our results indicate that cyclic thiosulfinate-mediated SOD1 stabilization should receive further attention as a potential therapeutic approach for fALS.

Dataset Information

Lamin A dimer and tetramer cross-links help explain disease mutations and polymer plasticity

Publications

Lamin A molecular compression and sliding as mechanisms behind nucleoskeleton elasticity.

Similar Datasets

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