title: Backbone resonance assignments of monomeric SOD1 in dilute and crowded environments.
abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to movement disorders. In motor neurons of ALS patients, intracellular aggregates of superoxide dismutase 1 (SOD1) have often been observed. To elucidate the aggregation mechanism, it is important to analyze the folding equilibrium of SOD1 between folded and aggregation-prone unfolded states. However, in most cases, this folding equilibrium has been studied in dilute solution even though the aggregate formation occurs in a highly crowded intracellular environment. Indeed, a recent study reported that the folding stability of SOD1 decreased in an environment containing protein crowder molecules. To understand such a destabilization effect due to protein crowders, it is necessary to obtain more precise structural information on SOD1 in the presence of protein crowders. Here, we report the1H,13C, and15N backbone resonance assignments of monomeric SOD1 in the absence and presence of the protein crowder lysozyme. The chemical shift differences caused by addition of lysozyme suggest that SOD1 associated with lysozyme via negatively charged surfaces. Based on the assigned chemical shifts, the presence of lysozyme has a limited influence on the secondary structure of SOD1. We anticipate that our assignments will provide an important basis for elucidation of the crowding-induced folding destabilization of SOD1.
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Iwakawa
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Morimoto
authors.affiliation: Department of Molecular and Cellular Physiology, Graduate School of Medicine, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.|Center for Medical Education, Graduate School of Medicine, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Erik
authors.initials: E
authors.lastname: Walinda
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugase
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan. shirakawa@moleng.kyoto-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shirakawa
mesh_terms: D006801:Humans; D008958:Models, Molecular; D009113:Muramidase / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D000072105:Superoxide Dismutase-1 / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000072105:Superoxide Dismutase-1; D009113:Muramidase
keywords: ALS; Folding destabilization; Lysozyme; Macromolecular crowding; Protein crowder; SOD1