Role of polysaccharide and lipid in lipopolysaccharide induced prion protein conversion.

ABSTRACT: Conversion of native cellular prion protein (PrP^c) from an ?-helical structure to a toxic and infectious ?-sheet structure (PrP^Sc) is a critical step in the development of prion disease. There are some indications that the formation of PrP^Sc is preceded by a ?-sheet rich PrP (PrP^?) form which is non-infectious, but is an intermediate in the formation of infectious PrP^Sc. Furthermore the presence of lipid cofactors is thought to be critical in the formation of both intermediate-PrP^? and lethal, infectious PrP^Sc. We previously discovered that the endotoxin, lipopolysaccharide (LPS), interacts with recombinant PrP^c and induces rapid conformational change to a ?-sheet rich structure. This LPS induced PrP^? structure exhibits PrP^Sc-like features including proteinase K (PK) resistance and the capacity to form large oligomers and rod-like fibrils. LPS is a large, complex molecule with lipid, polysaccharide, 2-keto-3-deoxyoctonate (Kdo) and glucosamine components. To learn more about which LPS chemical constituents are critical for binding PrP^c and inducing ?-sheet conversion we systematically investigated which chemical components of LPS either bind or induce PrP conversion to PrP^?. We analyzed this PrP conversion using resolution enhanced native acidic gel electrophoresis (RENAGE), tryptophan fluorescence, circular dichroism, electron microscopy and PK resistance. Our results indicate that a minimal version of LPS (called detoxified and partially de-acylated LPS or dLPS) containing a portion of the polysaccharide and a portion of the lipid component is sufficient for PrP conversion. Lipid components, alone, and saccharide components, alone, are insufficient for conversion.

SUBMITTER: Ladner-Keay CL 

PROVIDER: S-EPMC5161299 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature