Resolution-enhanced native acidic gel electrophoresis: A method for resolving, sizing, and quantifying prion protein oligomers

Abstract

The formation of β-sheet-rich prion protein (PrPβ) oligomers from native or cellular PrPc is thought to be a key step in the development of prion diseases. To assist in this characterization process we have developed a rapid and remarkably high resolution gel electrophoresis technique called RENAGE (resolution-enhanced native acidic gel electrophoresis) for separating, sizing, and quantifying oligomeric PrPβ complexes. PrPβ oligomers formed via either urea/salt or acid conversion can be resolved by RENAGE into a clear set of oligomeric bands differing by just one subunit. Calibration of the size of the PrPβ oligomer bands was made possible with a cross-linked mouse PrP90–232 ladder (1- to 11-mer) generated using ruthenium bipyridyl-based photoinduced cross-linking of unmodified proteins (PICUP). This PrP PICUP ladder allowed the size and abundance of PrPβ oligomers formed from urea/salt and acid conversion to be determined. This distribution consists of 7-, 8-, 9-, 10-, and 11-mers, with the most abundant species being the 8-mer. The high-resolution separation afforded by RENAGE has allowed us to investigate distinctive size and population changes in PrPβ oligomers formed under various conversion conditions, with various construct lengths, from various species or in the presence of anti-prion compounds.