tailieunhanh - Báo cáo khoa học: Synthesis and structural characterization of a mimetic membrane-anchored prion protein

During pathogenesis of transmissible spongiform encephalopathies (TSEs) an abnormal form (PrP Sc ) of the host encoded prion protein (PrP C ) accu-mulates in insoluble fibrils and plaques. The two forms of PrP appear to have identical covalent structures, but differ in secondary and tertiary structure. | ềFEBS Journal Synthesis and structural characterization of a mimetic membrane-anchored prion protein Matthew R. Hicks1 Andrew C. Gill2 Imanpreet K. Bath1 Atvinder K. Rullay3 Ian D. Sylvester2 David H. Crout3 and Teresa J. T. Pinheiro1 1 Department of BiologicalSciences University of Warwick Coventry UK 2 Institute for AnimalHealth Compton Newbury UK 3 Department of Chemistry University of Warwick Coventry UK Keywords prion GPI membranes conversion rafts Correspondence . Pinheiro Department of Biological Sciences University of Warwick Gibbet Hill Road Coventry CV4 7AL UK Fax 44 2476 523701 Tel 44 2476 528364 E-mail Received 21 December 2005 revised 19 January 2006 accepted 23 January 2006 doi During pathogenesis of transmissible spongiform encephalopathies TSEs an abnormal form PrPSc of the host encoded prion protein PrPC accumulates in insoluble fibrils and plaques. The two forms of PrP appear to have identical covalent structures but differ in secondary and tertiary structure. Both PrPC and PrPSc have glycosylphospatidylinositol GPI anchors through which the protein is tethered to cell membranes. Membrane attachment has been suggested to play a role in the conversion of PrPC to PrPSc but the majority of in vitro studies of the function structure folding and stability of PrP use recombinant protein lacking the GPI anchor. In order to study the effects of membranes on the structure of PrP we synthesized a GPI anchor mimetic GPIm which we have covalently coupled to a genetically engineered cysteine residue at the C-terminus of recombinant PrP. The lipid anchor places the protein at the same distance from the membrane as does the naturally occurring GPI anchor. We demonstrate that PrP coupled to GPIm PrP-GPIm inserts into model lipid membranes and that structural information can be obtained from this membrane-anchored PrP. We show that the structure of PrP-GPIm reconstituted in phosphatidylcholine and raft