NMR-STUDIES ON THE FLEXIBILITY OF THE POLIOVIRUS C3 LINEAR EPITOPE INSERTED INTO DIFFERENT SITES OF THE MALTOSE-BINDING PROTEIN

A set of permissive positions that tolerate insertions/deletions witho ut major deleterious consequences for the binding activity of the prot ein was previously identified in the maltose-binding protein, The C3 e pitope from poliovirus VP1 protein ((93)DNPASTTNKDK(103)) was inserted into eight of these positions and two nonpermissive control sites, NM R studies were performed on the MalE protein, the insertion/deletion m utants, and the C3MalE hybrids to selectively determine the flexible r egions in these proteins. Comparison of the C3 epitope mobility in the different hybrid proteins indicates that, whatever its insertion site and independently from the specific sequences of its linkers, the epi tope is mostly flexible, The vector protein was shown to unfold partia lly only in the two C3MalE hybrids that correspond to nonpermissive po sitions, For one of them (insertion at site 339), both sides of the in sert are flexible, and at most one side for all the other hybrids, Thi s result correlates with the antigenicity data on the inserted epitope (Martineau, P., Leclerc, C., and Hofnung, M. (1997) Mol. Immunol, in press.