Structure of a malaria parasite antigenic determinant displayed on filamentous bacteriophage determined by NMR spectroscopy: Implications for the structure of continuous peptide epitopes of proteins

The NANP repeating sequence of the circumsporozoite protein of Plasmodium f alciparum was displayed on the surface of fd filamentous bacteriophage as a 12-residue insert (NANP), in the N-terminal region of the major coat prote in (pVIII). The structure of the epitope determined by multidimensional sol ution NMR spectroscopy of the modified pVIII protein in lipid micelles was shown to be a twofold repeat of an extended and non-hydrogen-bonded loop ba sed on the sequence NPNA, demonstrating that the repeating sequence is NPNA , not NANP. Further, high resolution solid state NMR spectra of intact hybr id virions containing the modified pVIII. proteins demonstrate that the pep tides displayed on the surface of the virion adopt a single, stable conform ation; this is consistent with their pronounced immunogenicity as well as t heir ability to mimic the antigenicity of their native parent proteins.