Latest Medline Abstracts ... to July 28, 1996

Beta-sheet to alpha-helix change in a 142-residue polypeptide of prion protein
Variable transmissivity of Creutzfeldt-Jakob disease to rodents
A prion disease with a novel 96-base pair insertional mutation
Identification of a promoter region in the rat prion protein gene
Normal cellular isoform of the prion protein

Characterization of a 142-residue polypeptide of prion protein

Mehlhorn I; Groth D; Stockel J; Moffat B; Reilly D; Yansura D; Willett WS; Baldwin M; Fletterick R; Cohen FE; Vandlen R; Henner D; Prusiner SB

Department of Neurology, University of California, San Francisco 94143, USA.

Biochemistry 35: 5528-37 (1996)

The major, and possible only, component of the infectious prion is the scrapie prion protein (PrPSc); the protease resistant core of PrPSc is PrP 27-30, a protein of approximately 142 amino acids. PrPSc is derived from the cellular PrP isoform (PrPC) by a post-translational process in which a profound conformational change occurs. Syrian hamster (SHa) PrP genes of varying length ranging from the N- and C- terminally truncated 90-228 up to the full-length mature protein 23-231 were inserted into Escherichia coli deficient for proteases. Maximum expression was obtained for a truncated SHaPrP containing residues 90-231, which correspond to the sequence of PrP 27-30; from each liter of E. coli culture, approximately 50 mg of purified rPrP was obtained.

The secondary structure of rPrP was determined by circular dichroism and Fourier transform infrared spectroscopy. When rPrP was purified under reducing conditions, it had a high beta-sheet content and relatively low solubility similar to PrPSc, particularly at pH values > 7. Refolding of rPrP by oxidation to form a disulfide bond between the two Cys residues of this polypeptide produced a soluble protein with a high alpha-helical content similar to PrPC.

These multiple conformations of rPrP are reminiscent of the structural plurality that characterizes the naturally occurring PrP isoforms. The high levels of purified rPrP which can now be obtained should facilitate determination of the multiple tertiary structures that Prp can adopt.


Transmission of Creutzfeldt-Jakob disease to rodents

Tateishi J; Kitamoto T; Hoque MZ; Furukawa H

Department of Neuropathology, Neurological Institute
Faculty of Medicine, Kyushu University, Fukuoka, Japan.

Neurology 46: 532-7 (1996)

Sporadic Creutzfeldt-Jakob disease (CJD) with 129M/M, and iatrogenic and familial CJD with E200K and M232R, showed similar clinicopathologic features, a synaptic type deposition of PrPCJD, and high transmission frequencies to mice. Sporadic patients with 129M/V or 129V/V, and mutation cases with V180I, showed slightly different features and low or null transmission frequencies to mice. Hereditary cases with P102L, P105L, A117V, Y145stop, and insertions had different features but all demonstrated a long clinical duration and the presence of PrP plaques.

The experimental transmission to mice of these mutant forms was difficult, except for one-third of the cases with P102L. CJD and related diseases, even those that are hereditary, may thus be divided into two different groups, those that are easily transmissible and those that are either difficult to transmit or nontransmissible.


A prion disease with a novel 96-base pair insertional mutation

Campbell TA; Palmer MS; Will RG; Gibb WR; Luthert PJ; Collinge J
Prion Disease Group, Department of Biochemistry and Molecular Genetics, St. Mary's Hospital Medical School, London, UK.
Neurology 46: 761-6 (1996)

There are coding mutations in the prion protein gene in familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease, and other phenotypes that make up the inherited prion diseases. Insertional mutations consisting of two, five, six, seven, eight, and nine additional octapeptide repeat elements are seen in the inherited prion diseases and usually present as atypical dementias with considerable intrafamilial phenotypic variability. A four-octarepeat insertion was reported previously in an individual without neurodegenerative disease who died of hepatic cirrhosis.

Here we report a novel four-octarepeat insertional mutation in a case with classical clinical, electroencephalographic and histopathologic features of CJD with the unusual finding of pronounced prion protein immunoreactivity of the molecular layer of the cerebellum.


Identification of a promoter region in the rat prion protein gene

Saeki K; Matsumoto Y; Matsumoto Y; Onodera T 
Department of Molecular Immunology, Faculty of Agriculture
University, of Tokyo, Japan

Biochem Biophys Res Commun 219: 47-52 (1996)
We have demonstrated the presence of a rat prion protein (RaPrP) gene promoter upstream of multiple initiation sites. A 0.1-kb fragment upstream of the 5'-untranslated region contains specific DNA motifs characteristic of promoter elements including an AP-1 binding site, an inverted CCAAT motif and three inverted Sp-1 binding sites. This fragment directs transcription of a luciferase reporter gene in pheochromocytoma cells (PC12) and rat glioma cells (C6), suggesting that it contains the promoter for the RaPrP gene. To more precisely localize the transcription regulatory elements in this region, a series of 5'-deletion mutants were generated. Deletion analysis showed that an inverted CCAAt and adjoining Sp-1 binding sequences may play an important role in transcription of the RaPrP gene.

Normal cellular isoform of the prion protein

Pergami P; Jaffe H; Safar J

The purified PrPC was a monomer with an intact N-terminus, and with a Stoke's radius of 26 A, corresponding to that expected from the molecular weight for a native protein. The presence of the native-like conformation was further verified by peptide mapping after limited trypsin proteolysis, and by the apparent unfolding in guanidine hydrochloride