Neurology. 2000 Oct 10;55(7):1055-7. A new mutation in the prion protein gene: a patient with dementia and white matter changes.
van Harten B, van Gool WA, Van Langen IM, Deekman JM, Meijerink PH, Weinstein HC.
Department of Neurology, Sint Lucas Andreas Hospital, Amsterdam, The Netherlands.
The authors describe the clinical characteristics, MRI abnormalities, and molecular findings in a patient with a novel variant of a two-octarepeat insertion mutation in the prion protein gene. This patient presented with moderately progressive dementia of presenile onset and gait ataxia. MRI showed extensive cortical atrophy and white matter abnormalities. The mutation consists of a two-octarepeat insertion mutation and irregularities in the nucleotide sequence of the octarepeat region.
PMID:_11061272
J Biol Chem. 2001 Jan 26;276(4):2427-31. Epub 2000 Nov 07. The role of disulfide bridge in the folding and stability of the recombinant human prion protein.
Maiti NR, Surewicz WK.
Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
It is believed that the critical step in the pathogenesis of transmissible spongiform encephalopathies is a transition of prion protein (PrP) from an alpha-helical conformation, PrP(C), to a beta-sheet-rich form, PrP(Sc). Native prion protein contains a single disulfide bond linking Cys residues at positions 179 and 214. To elucidate the role of this bridge in the stability and folding of the protein, we studied the reduced form of the recombinant human PrP as well as the variant of PrP in which cysteines were replaced with alanine residues. At neutral pH, the reduced prion protein and the Cys-free mutant were insoluble and formed amorphous aggregates. However, the proteins could be refolded in a monomeric form under the conditions of mildly acidic pH. Spectroscopic experiments indicate that the monomeric Cys-free and reduced PrP have molten globule-like properties, i.e. they are characterized by compromised tertiary interactions, an increased exposure of hydrophobic surfaces, lack of cooperative unfolding transition in urea, and partial loss of native (alpha-helical) secondary structure. In the presence of sodium chloride, these partially unfolded proteins undergo a transition to a beta-sheet-rich structure. However, this transition is invariably associated with protein oligomerization. The present data argue against the notion that reduced prion protein can exist in a stable monomeric form that is rich in beta-sheet structure.
PMID:_11069909
Biochem J. 2000 Nov 15;352 Pt 1:191-6. Bovine prion protein as a modulator of protein kinase CK2.
Meggio F, Negro A, Sarno S, Ruzzene M, Bertoli A, Sorgato MC, Pinna LA.
Dipartimento di Chimica Biologica, Universita di Padova, Viale G. Colombo 3, 35121 Padova, Italy.
On the basis of far-Western blot and plasmon resonance (BIAcore) experiments, we show here that recombinant bovine prion protein (bPrP) (25-242) strongly interacts with the catalytic alpha/alpha' subunits of protein kinase CK2 (also termed 'casein kinase 2'). This association leads to increased phosphotransferase activity of CK2alpha, tested on calmodulin or specific peptides as substrate. We also show that bPrP counteracts the inhibition of calmodulin phosphorylation promoted by the regulatory beta subunits of CK2. A truncated form of bPrP encompassing the C-terminal domain (residues 105-242) interacts with CK2 but does not affect its catalytic activity. The opposite is found with the N-terminal fragment of bPrP (residues 25-116), although the stimulation of catalysis is less efficient than with full-size bPrP. These results disclose the potential of the PrP to modulate the activity of CK2, a pleiotropic protein kinase that is particularly abundant in the brain.
PMID:_11062072
Neuroradiology. 2000 Sep;42(9):662-5. Proton magnetic resonance spectroscopy of a patient with Gerstmann-Straussler-Scheinker disease.
Konaka K, Kaido M, Okuda Y, Aoike F, Abe K, Kitamoto T, Yanagihara T.
Department of Neurology, Osaka University Graduate School of Medicine, Suita city, Japan.
A 23-year-old woman with Gerstmann-Straussler-Scheinker disease (GSS) was investigated by 1H-magnetic resonance spectroscopy (1H-MRS). She developed gait ataxic at 22 years. The diagnosis was confirmed by DNA analysis showing a proline-to-leucine point mutation at codon 102 of the prion protein. On 1H-MRS, she showed a remarkable reduction of the N-acetylaspartate/creatine ratio in the frontal lobe, cerebellar hemisphere and vermis and putamen. MRI revealed mild atrophy of the cerebellar hemispheres and vermis and cerebral cortex, but single-photon emission computed tomography (SPECT) with 99mHMPAO showed normal perfusion in the cerebellum. The imaging studies suggest that MRS might be superior to MRI or SPECT for detection of early neuronal degeneration.
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