Design and Characterization of an Optogenetic Tool to Investigate the Neurotoxicity of Escherichia coli Amyloid CsgA Fimbriae in Caenorhabditis elegans

Abstract

Previous studies on bacterial amyloids (like curli from E.coli) have shown that some have the capacity to cross – seed with human neural proteins (Friedland et al., 2020) and induce cell toxicity (Molina-García et al., 2017, Revilla García, 2019). Moreover, it has been seen that curli has the ability to reach neurons in Caenorhabditis elegans (C. elegans) model (C. Wang et al., 2021).Nevertheless, it has not been studied if these functional bacterial amyloids (FUBAs) have the capacity to induce neurotoxicity per se. In this study we designed and characterized an optogenetic fusion protein, CsgA-CRYmCherry based on a tool already developed for the Aß peptide (Lim et al., 2020) to investigate the neurotoxic potential of curli major subunit CsgA in C. elegans. This animal model will permit us to investigate the neurotoxic pathways as it has its entire connectome mapped out. The construct enables light dependent oligomerization of CsgA in vivo allowing the control of its aggregation. Moreover, we also designed an Aß-CRY-mCherry plasmid as a possitive control for neurotoxicity. We show through Congo Red assays in E. coli mutants a potential light-induced amyloid formation of the CsgA-CRY-mCherry plasmid, yet, protein expression was not able to be detected by western blot due to technical limitations.