TL;DR: Semi-denaturating detergent agarose gel electrophoresis (SDD-AGE) is a technique that takes advantage of both the property of prions and prion-like polymers to be highly resistant to solubilization by SDS detergent, and the large pores sizes of agaroses that allow the resolution of high molecular weight complexes.
Abstract: [] Pathological proteins in neurodegenerative diseases suffer a conformational change to a misfolded amyloid state. Such pathological event leads to the aggregation of these proteins that indefinitely propagates as an altered form of itself, and harbor prion-like properties (Wickner, 1994; Prusiner, 2012). In addition to diseases, prions can also have beneficial adaptive roles in lower eukaryotes (in fungi and yeast) (Eaglestone et al., 1999; True et al., 2004; Coustou et al., 1999). Besides separating polymers from their precursor soluble monomers, another particular difficulty of the study of amyloid proteins is to resolve the heterogeneity of the aggregates, since these usually exhibit a variable degree of polymorphism. Semi-denaturating detergent agarose gel electrophoresis (SDD-AGE) is a technique that takes advantage of both the property of prions and prion-like polymers to be highly resistant to solubilization by SDS detergent, and the large pores sizes of agarose, that allow the resolution of high molecular weight complexes. In this method, we describe in detail how this technique can be used to characterize heterogeneous aggregation in bacteria and yeast (Gasset-Rosa et al., 2014; Molina-Garcia and Giraldo, 2014), and further be applied to study the aggregation pattern of proteins that become prone to aggregation through genetic manipulation.
TL;DR: An adaptation of this technique that facilitates its use in large-scale applications, such as screens for novel prions and other amyloidogenic proteins, is demonstrated, which uses capillary transfer for greater reliability and ease of use, and allows any sized gel to be accomodated.
Abstract: Amyloid aggregation is associated with numerous protein misfolding pathologies and underlies the infectious properties of prions, which are conformationally self-templating proteins that are thought to have beneficial roles in lower organisms. Amyloids have been notoriously difficult to study due to their insolubility and structural heterogeneity. However, resolution of amyloid polymers based on size and detergent insolubility has been made possible by Semi-Denaturing Detergent-Agarose Gel Electrophoresis (SDD-AGE). This technique is finding widespread use for the detection and characterization of amyloid conformational variants. Here, we demonstrate an adaptation of this technique that facilitates its use in large-scale applications, such as screens for novel prions and other amyloidogenic proteins. The new SDD-AGE method uses capillary transfer for greater reliability and ease of use, and allows any sized gel to be accomodated. Thus, a large number of samples, prepared from cells or purified proteins, can be processed simultaneously for the presence of SDS-insoluble conformers of tagged proteins.