HOMEWORK#2

1. The 1997 Nobel Prize in Physiology or Medicine is awarded to the
American Stanley Prusiner for his pioneering discovery of Prions - a new
biological principle of infection. Stanley Prusiner has added prions to the list
of well known infectious agents including bacteria, viruses, fungi and
parasites. Please find his recently published paper concerning prion diseases
and the BSE crisis. Please show the abstract on your homepage and tell me
what is BSE.

ANSWER:

Science 1997 Oct 10;278(5336):245-251

[MEDLINE record in process]

Prion diseases and the BSE crisis.

Prusiner SB

Department of Neurology (address for correspondence) and Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143, USA. Bovine spongiform encephalopathy (BSE) and human Creutzfeldt-Jakob disease (CJD) are among the most notable central nervous system degenerative disorders caused by prions. CJD may present as a sporadic, genetic, or infectious illness. Prions are transmissible particles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein (PrPSc). The normal, cellular prion protein (PrPC) is converted into PrPSc through a posttranslational process during which it acquires a high beta-sheet content. It is thought that BSE is a result of cannibalism in which faulty industrial practices produced prion-contaminated feed for cattle. There is now considerable concern that bovine prions may have been passed to humans, resulting in a new form of CJD.

2.How many papers is referecned in Medline, on line biomedical abstract
service, about prion? How many is concerning its structure? Can you find the
paper describe the structure of mouse prion? Please show its abstract on
your homepage.

ANSWER:

1.用prion在medline中搜尋,找到1306篇有關prion的papers

2.用prion AND structure 在medline中搜尋,找到167篇有關prion structure的papers

3.用prion AND structure AND mouse在medline中搜尋,找到28篇有關prion structure and mouse的papers

4.從這28篇中找到2篇與the structure of mouse prion有關的papers之abstract,如下:

Proc Natl Acad Sci U S A 1997 Jul 8;94(14):7281-7285

Prion protein NMR structure and species barrier for prion diseases.

Billeter M, Riek R, Wider G, Hornemann S, Glockshuber R, Wuthrich K

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.



Nature 1996 Jul 11;382(6587):180-182

NMR structure of the mouse prion protein domain PrP(121-321).

Riek R, Hornemann S, Wider G, Billeter M, Glockshuber R, Wuthrich K

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.