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 the 1H, 13C, and 15N 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.
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Acknowledgements
We thank Dr. Jens Danielsson and Ms. Sarah Leeb for kindly providing the expression plasmid for SOD1. We are also thankful to Dr. Jens Danielsson for constructive discussions. This work was supported by the scholar project of Toyota Physical and Chemical Research Institute, and by JSPS KAKENHI Grant Number JP26119004.
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Naoto Iwakawa and Daichi Morimoto have contributed equally to this work.
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Iwakawa, N., Morimoto, D., Walinda, E. et al. Backbone resonance assignments of monomeric SOD1 in dilute and crowded environments. Biomol NMR Assign 11, 81–84 (2017). https://doi.org/10.1007/s12104-016-9724-5
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DOI: https://doi.org/10.1007/s12104-016-9724-5