Refolding-assisted purification of native full-length TDP-43 compatible with BSL-2 safety regulations.

TAR DNA-binding protein 43 (TDP-43) is a prion-like RNA-binding protein that plays a key role in amyotrophic lateral sclerosis and frontotemporal dementia. Producing full-length TDP-43 consistently is thus relevant for its in vitro studies and yet it remains challenging, especially with the current requirement to work under biosafety level-2 (BSL-2) containment due to new safety regulations for Prion-like and amyloidogenic proteins. Here we describe a refolding-assisted purification protocol for TDP-43 from soluble fraction that can be implemented with basic equipment in standard BSL-2 laboratories. Expression in Escherichia coli is followed by IMAC-capture on an EDTA/DTT-tolerant Ni