Modulating the Folding Landscape of Superoxide Dismutase 1 with Targeted Molecular Binders

Amyotrophic lateral sclerosis, or Lou Gehrig's disease, is characterized by motor neuron death with average survival times of 2 ‐ 5 years. One cause of this disease is the misfolding of superoxide dismutase 1 (SOD1), a protein whose stability and aggregation propensity are affected by point mutations spanning the protein. Here, we use an epitope‐specific, high‐throughput screen to identify peptides that both stabilize the native conformation of SOD1 as well as accelerate its folding by 2.5‐fold. Ligands targeted to the electrostatic loop on the periphery of the protein tightened the non‐metalated structure and accelerated its folding. This strategy may be useful for fundamental studies of protein energy landscapes as well as designing new classes of therapeutics

Modulating SOD1 Folding Landscapes with Targeted Molecular Binders

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the deterioration of motor neurons that abates essential biological functions and exhibits survival times of 3 - 5 years after diagnosis. One driver of this disease derives from inherited mutations to the protein superoxide dismutase 1 (SOD1), which hinder proper folding and result in the accumulation of toxic aggregates. We identified cyclic peptides that target precise epitopes on SOD1 through an emerging screening platform that furnishes high-affinity binders against regions of a protein independent of secondary or tertiary structure. Binding these epitopes both stabilizes the native state and accelerates folding. In this context, these small peptides function as molecular chaperones and mitigate the impact of deleterious mutations to SOD1. They also display the traditional benefits of small molecules, such as straightforward chemical modifications and long-term stability. Overall, this method provides a route to rationally perturb the energy landscape of any protein through noncovalent binding, making it useful in fundamental studies of protein folding as well as designing therapeutics for misfolding diseases

Molecular Modulation of Protein Energy Landscapes

Protein catalyzed capture agents are an emerging class of oligopeptides that combine the benefits of small molecules and antibodies to furnish ligands with picomolar binding affinity, serum stability, and cell permeability. Their identification involves screening a synthetic, alkyne-functionalized epitope from a target protein against a library of cyclic peptides bearing terminal azides. We identified ligands that bind regions of superoxide dismutase 1 (SOD1), a protein that misfolds to cause amyotrophic lateral sclerosis (ALS), consistently destabilized upon mutation. Treatment of the disease is challenging because there are over 180 heritable mutations of SOD1 and virtually no well-defined binding sites addressable by traditional ligand identification strategies. These mutations ultimately cause the protein to adopt toxic conformations that aggregate and damage cellular functions within the central nervous system. PCC agents targeting regions consistently destabilized across several mutations bind and stabilize its native conformation. We characterized the impact of binding, both on the ground state stability of several mutants as well as the kinetics of SOD1 folding and denaturation

Molecular Modulation of Protein Energy Landscapes

Protein catalyzed capture agents are an emerging class of oligopeptides that combine the benefits of small molecules and antibodies to furnish ligands with picomolar binding affinity, serum stability, and cell permeability. Their identification involves screening a synthetic, alkyne-functionalized epitope from a target protein against a library of cyclic peptides bearing terminal azides. We identified ligands that bind regions of superoxide dismutase 1 (SOD1), a protein that misfolds to cause amyotrophic lateral sclerosis (ALS), consistently destabilized upon mutation. Treatment of the disease is challenging because there are over 180 heritable mutations of SOD1 and virtually no well-defined binding sites addressable by traditional ligand identification strategies. These mutations ultimately cause the protein to adopt toxic conformations that aggregate and damage cellular functions within the central nervous system. PCC agents targeting regions consistently destabilized across several mutations bind and stabilize its native conformation. We characterized the impact of binding, both on the ground state stability of several mutants as well as the kinetics of SOD1 folding and denaturation

Protein-catalyzed capture agents targeting misfolded superoxide dismutase 1

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons in the brain and spinal cord. Familial ALS can be caused by mutant isoforms of superoxide dismutase 1 (SOD1) that lead the protein to misfold and adopt toxic conformations. Over 180 mutations in SOD1 are linked to the disease, making it a challenging therapeutic target. Protein-catalyzed capture (PCC) agents are ligands assembled through in situ click chem. that can bind a protein to stabilize its native conformation. The objective of this project is to develop PCC agents that target SOD1 mutants and reduce misfolding. We used an epitope-targeted screen to identify oligopeptides that bind the electrostatic loop (a region of the protein destabilized upon mutation) and an internal fragment (revealed upon misfolding). We anticipate that the PCC agents against the internal fragment and precleared against the electrostatic loop will bind misfolded SOD1 selectively, while the PCC agents against the electrostatic loop will detect folded SOD1. This will allow us to discriminate between the folded and misfolded species. Screens against the electrostatic loop yielded a PCC agent with promising ability to recognize SOD1. Ultimately, this ligand might be used to mitigate aggregation of mutant isoforms and treat ALS

Protein-catalyzed capture agents targeting misfolded superoxide dismutase 1

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons in the brain and spinal cord. Familial ALS can be caused by mutant isoforms of superoxide dismutase 1 (SOD1) that lead the protein to misfold and adopt toxic conformations. Over 180 mutations in SOD1 are linked to the disease, making it a challenging therapeutic target. Protein-catalyzed capture (PCC) agents are ligands assembled through in situ click chem. that can bind a protein to stabilize its native conformation. The objective of this project is to develop PCC agents that target SOD1 mutants and reduce misfolding. We used an epitope-targeted screen to identify oligopeptides that bind the electrostatic loop (a region of the protein destabilized upon mutation) and an internal fragment (revealed upon misfolding). We anticipate that the PCC agents against the internal fragment and precleared against the electrostatic loop will bind misfolded SOD1 selectively, while the PCC agents against the electrostatic loop will detect folded SOD1. This will allow us to discriminate between the folded and misfolded species. Screens against the electrostatic loop yielded a PCC agent with promising ability to recognize SOD1. Ultimately, this ligand might be used to mitigate aggregation of mutant isoforms and treat ALS

Noncovalent modulation of protien energy landscapes with targeted molecular binders

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the deterioration of motor neurons that abates essential biol. functions and exhibits survival times of 3 - 5 years after diagnosis. One driver of this disease derives from inherited mutations to the protein superoxide dismutase 1 (SOD1), which hinder proper folding and result in the accumulation of toxic aggregates. We identified cyclic peptides that target precise epitopes on SOD1 through an emerging screening platform that furnishes high-affinity binders against regions of a protein independent of secondary and tertiary structure. Binding these epitopes both stabilizes the native state and accelerates folding. In this context, these small peptides function as mol. chaperones and mitigate the impact of deleterious mutations to SOD1. They also display the traditional benefits of small mols., such as straightforward chem. modifications and long-term stability. Overall, this method provides a route to rationally perturb the energy landscape of any protein through noncovalent binding, making it useful in fundamental studies of protein folding as well as designing therapeutics for misfolding diseases