Comparison of two synthetically generated recombinant prions
Yi Zhang, Fei Wang, Xinhe Wang, Zhihong Zhang, Yuanyuan Xu, Guohua Yu, Chonggang Yuan and Jiyan Ma
Prion is a protein-conformation-based infectious agent causing fatal neurodegenerative diseases in humans and animals. Our previous studies revealed that in the presence of cofactors, infectious prions can be synthetically generated in vitro with bacterially expressed recombinant prion protein (PrP). Once initiated, the recombinant prion is able to propagate indefinitely via serial protein misfolding cyclic amplification (sPMCA). In this study, we compared 2 separately initiated recombinant prions. Our results showed that these 2 recombinant prions had distinct biochemical properties and caused different patterns of spongiosis and PrP deposition in inoculated mice. Our findings indicate that various recombinant prions can be initiated in vitro and potential reasons for this variability are discussed.
Lipopolysaccharide Induced Conversion of Recombinant Prion Protein
Fozia Saleem, Trent C Bjorndahl, Carol L Ladner, Rolando Perez-Pinero, Burim N Ametaj and David Wishart
The conformational conversion of the cellular prion protein (PrPC) to the beta-rich infectious isoform PrPSc is considered a critical and central feature in prion pathology. Although PrPSc is the critical component of the infectious agent, as proposed in the 'protein-only' prion hypothesis, cellular components have been identified as important cofactors in triggering and enhancing the conversion of PrPC to proteinase K resistant PrPSc. A number of in vitro systems using various chemical and/or physical agents such as guanidine hydrochloride, urea, SDS, high temperature and low pH, have been developed that cause PrPC conversion, their amplification, and amyloid fibril formation often under non-physiological conditions. In our ongoing efforts to look for endogenous and exogenous chemical mediators that might initiate, influence or result in the natural conversion of PrPC to PrPSc, we discovered that lipopolysaccharide (LPS), a component of gram-negative bacterial membranes interacts with recombinant prion proteins and induces conversion to an isoform richer in beta sheet at near physiological conditions as long as the LPS concentration remains above the critical micelle concentration (CMC). More significant was the LPS mediated conversion that was observed even at sub-molar ratios of LPS to recombinant ShPrP (90-232).
Regional distribution of anchorless prion protein, PrP226*, in the human brain
Anja Lukan, Maja Černilec, Tanja Vranac, Mara Popović and Vladka Čurin Šerbec
It was shown previously that truncated molecules of prion protein can be found in brains of patients with some types of transmissible spongiform encephalopathy. One such molecule, PrP226*, is a fragment of prion protein, truncated at Tyr226. It was found to be present in aggregates, from which it can be released using chaotropic salts. In this study we investigated the distribution of PrP226* in Creutzfeldt–Jakob disease affected human brain, employing the mAb V5B2, specifically recognizing this fragment. The results show that PrP226* is not evenly distributed among different regions of human brain. Among brain regions analyzed, the fragment was found most likely to be accumulated in the cerebellum. Its distribution correlates with the distribution of PrPSc.
The relationship between amyloid structure and cytotoxicity
Karen E Marshall, Ricardo Marchante, Wei-Feng Xue and Louise C Serpell
Self-assembly of proteins and peptides into amyloid structures has been the subject of intense and focused research due to their association with neurodegenerative, age-related human diseases and transmissible prion diseases in humans and mammals. Of the disease associated amyloid assemblies, a diverse array of species, ranging from small oligomeric assembly intermediates to fibrillar structures, have been shown to have toxic potential. Equally, a range of species formed by the same disease associated amyloid sequences have been found to be relatively benign under comparable monomer equivalent concentrations and conditions. In recent years, an increasing number of functional amyloids have also been found. These developments show that not all amyloid structures are generically toxic to cells. Given these observations, it is important to understand why amyloid structures may encode such varied toxic potential despite sharing a common core molecular architecture. Here, we discuss possible links between different aspects of amyloidogenic structures and assembly mechanisms with their varied functional effects. We propose testable hypotheses for the relationship between amyloid structure and its toxic potential in the context of recent reports on amyloid sequence, structure, and toxicity relationships.