Proc Natl Acad Sci U S A 1997 Jul 8;94(14):7281-7285
Institut fur Molekularbiologie und Biophysik, Eidgenossische Technische Hochschule, CH-8093 Zurich, Switzerland.
The structural basis of species specificity of transmissible spongiform encephalopathies, such as bovine spongiform encephalopathy or "mad cow disease" and Creutzfeldt-Jakob disease in humans, has been investigated using the refined NMR structure of the C-terminal domain of the mouse prion protein with residues 121-231. A database search for mammalian prion proteins yielded 23 different sequences for the fragment 124-226, which display a high degree of sequence identity and show relevant amino acid substitutions in only 18 of the 103 positions. Except for a unique isolated negative surface charge in the bovine protein, the amino acid differences are clustered in three distinct regions of the three-dimensional structure of the cellular form of the prion protein. Two of these regions represent potential species-dependent surface recognition sites for protein-protein interactions, which have independently been implicated from in vitro and in vivo studies of prion protein transformation. The third region consists of a cluster of interior hydrophobic side chains that may affect prion protein transformation at later stages, after initial conformational changes in the cellular protein.
PMID: 9207082, MUID: 97352789
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Nature 1996 Jul 11;382(6587):180-182
Institut fur Molekularbiologie und Biophysik, Eidgenossische Technische Hochschule-Honggerberg, Zurich, Switzerland.
The 'protein only' hypothesis states that a modified form of normal prion protein triggers infectious neurodegenerative diseases, such as bovine spongiform encephalopathy (BSE), or Creutzfeldt-Jakob disease (CJD) in humans. Prion proteins are thought to exist in two different conformations: the 'benign' PrPcform, and the infectious 'scrapie form', PrPsc. Knowledge of the three-dimensional structure of PrPc is essential for understanding the transition to PrPsc. The nuclear magnetic resonance (NMR) structure of the autonomously folding PrP domain comprising residues 121-231 (ref. 6) contains a two-stranded antiparallel beta-sheet and three alpha-helices. This domain contains most of the point-mutation sites that have been linked, in human PrP, to the occurrence of familial prion diseases. The NMR structure shows that these mutations occur within, or directly adjacent to, regular secondary structures. The presence of a beta-sheet in PrP(121-231) is in contrast with model predictions of an all-helical structure of PrPc (ref. 8), and may be important for the initiation of the transition from PrPc to PrPsc.
PMID: 8700211, MUID: 96317593
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