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Báo cáo sinh học : "Prion variants, species barriers, generation and propagation"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Prion variants, species barriers, generation and propagation. | Journal of Biology BioMed Central Minireview Prion variants species barriers generation and propagation Reed B Wickner Herman K Edskes Frank Shewmaker Dmitry Kryndushkin and Julie Nemecek Address Laboratory of Biochemistry and Genetics National Institute of Diabetes Digestive and Kidney Diseases National Institutes of Health Bethesda MD 20892-0830 USA. Correspondence Reed B Wickner. Email wickner@helix.nih.gov Published 26 May 2009 Journal of Biology 2009 8 47 doi 10.1186 jbiol148 The electronic version of this article is the complete one and can be found online at http jbiol.com content 8 5 47 2009 BioMed Central Ltd Abstract Prion variants faithfully propagate across species barriers but if the barrier is too high new variants mutants are selected as shown in a recent BMC Biology report. Protein sequence alteration can prevent accurate structural templating at filament ends producing prion variants. Prions are infectious proteins able to propagate and transmit the infection from one individual to another without an essential nucleic acid. In addition to this horizontal transmission typical of the mammalian transmissible spongiform encephalopathies TSEs prions of fungi also transmit the infection vertically to their offspring and so they are proteins acting as genes just as nucleic acids can act as enzymes Table 1 . Most prions are amyloids - filamentous polymers high in P-sheet structure usually protease resistant and with characteristic staining properties. Prion transmission occurs when donor amyloid enters the recipient cell and the equivalent recipient protein joins to the ends of the amyloid filaments which act as a structural template so that the recipient protein adopts usually the same conformation as the donor amyloid. The known prion-forming proteins of yeast and mammals are listed in Table 1. A single prion protein sequence can form any of several biologically distinct prion strains or variants differentiated in mammals by incubation time disease signs