title: Local unfolding and aggregation mechanisms of SOD1: a Monte Carlo exploration.
abstract: Copper, zinc superoxide dismutase 1 (SOD1) is a ubiquitous homodimeric enzyme, whose misfolding and aggregation play a potentially key role in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). SOD1 aggregation is thought to be preceded by dimer dissociation and metal loss, but the mechanisms by which the metal-free monomer aggregates remain incompletely understood. Here we use implicit solvent all-atom Monte Carlo (MC) methods to investigate the local unfolding dynamics of the β-barrel-forming SOD1 monomer. Although event-to-event variations are large, on average, we find clear differences in dynamics among the eight strands forming the β-barrel. Most dynamic is the eighth strand, β8, which is located in the dimer interface of native SOD1. For the four strands in or near the dimer interface (β1, β2, β7, and β8), we perform aggregation simulations to assess the propensity of these chain segments to self-associate. We find that β1 and β2 readily self-associate to form intermolecular parallel β-sheets, whereas β8 shows a very low aggregation propensity.
authors.affiliation: Computational Biology and Biological Physics, Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE-223 62 Lund, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Bille
authors.forename: Sigurdur Æ
authors.initials: SÆ
authors.lastname: Jónsson
authors.forename: Mikael
authors.initials: M
authors.lastname: Akke
authors.forename: Anders
authors.initials: A
authors.lastname: Irbäck
mesh_terms: D000595:Amino Acid Sequence; D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000473:pathology; D003300:Copper / Q000737:chemistry; D019281:Dimerization; D006801:Humans; D009010:Monte Carlo Method; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D015032:Zinc / Q000737:chemistry
chemical_list: C000606290:SOD1 protein, human; D003300:Copper; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D015032:Zinc