NMR CHARACTERIZATION OF THE FULL-LENGTH RECOMBINANT MURINE PRION PROTEIN, MPRP(23-231)

The recombinant murine prion protein, mPrP(23-231), was expressed in E . coli with uniform N-15-labeling, NMR experiments showed that the pre viously determined globular three-dimensional structure of the C-termi nal domain mPrP(121-231) is preserved in the intact protein, and that the N-terminal polypeptide segment 23-120 is flexibly disordered, This structural information is based on nearly complete sequence-specific assignments for the backbone amide nitrogens, amide protons and a-prot ons of the polypeptide segment of residues 121-231 in mPrP(23-231). Co incidence of corresponding sequential and medium-range nuclear Overhau ser effects (NOE) showed that the helical secondary structures previou sly identified in mPrP(121-231) are also present in mPrP(23-231), and near-identity of corresponding amide nitrogen and amide proton chemica l shifts indicates that the three-dimensional fold of mPrP(121-231) is also preserved in the intact protein. The linewidths in heteronuclear H-1-N-15 correlation spectra and N-15{H-1}-NOEs showed that the well structured residues 126-230 have correlation times of several nanoseco nds, as is typical for small globular proteins, whereas correlation ti mes shorter than 1 nanosecond were observed for all residues of mPrP(2 3-231) outside of this domain. (C) 1997 Federation of European Biochem ical Societies.