Nucleic acid binding proteins in highly purified Creutzfeldt-Jakob disease preparations.

Abstract

The nature of the infectious agent causing human Creutzfeldt-Jakob disease (CJD), a slowly progressive dementia, is controversial. As in scrapie, no agent-specific proteins or nucleic acids have been identified. However, biological features of exponential replication and agent strain variation, as well as physical size and density data, are most consistent with a viral structure--i.e., a nucleic acid-protein complex. It is often assumed that nuclease treatment, which does not reduce infectious titer, leaves no nucleic acids of > 50 bp. However, nucleic acids of 500-6000 bp can be extracted from highly purified infectious complexes with a mass of approximately 1.5 x 10(7) daltons. It was therefore germane to search for nucleic acid binding proteins that might protect an agent genome. We here use Northwestern blotting to show that there are low levels of nonhistone nucleic acid binding proteins in highly purified infectious 120S gradient fractions. Several nucleic acid binding proteins were clearly host encoded, whereas others were apparent only in CJD, but not in parallel preparations from uninfected brain. Small amounts of residual host Gp34 (prion protein) did not bind any 32P-labeled nucleic acid probes. Most of the minor "CJD-specific" proteins had an acidic pI, a characteristic of many viral core proteins. Such proteins deserve further study, as they probably contribute to unique properties of resistance described for these agents. It remains to be seen if any of these proteins are agent encoded.

Scrapie-like prion protein is translocated to the nuclei of infected cells independently of proteasome inhibition and interacts with chromatin

“…Given the in vitro DNA-binding properties of recombinant PrP (Gabus et al, 2001a;Gabus et al, 2001b;Sklaviadis et al, 1993), we were interested to know how nuclear PrP would fractionate with respect to various chromatin extraction procedures. DNAbound proteins can be released from chromatin by different treatments such as DNase and NaCl (Lichota and Grasser, 2001;Tatsumi et al, 2000).…”

Viral particles are required for infection in neurodegenerative Creutzfeldt-Jakob disease.

“…Subfraction recoveries totaled 85-90%. Detection of binding proteins with 32p-labeled RNA in B was done as described (16). been well established, it could have been considered a crucial infectious protein in our viral titrations.…”

Acute Formation of Protease-resistant Prion Protein Does Not Always Lead to Persistent Scrapie Infection in Vitro

“…Such strain-specific factors could include an as yet unidentified scrapie-specific nucleic acid as well as other protein and nonprotein components that may be closely associated with PrPres (33)(34)(35)(36)(37)(38). Strain specificity might also be encoded by the conformation of the PrP-res molecule (39 -41).…”