Raman spectroscopic study on the conformation of a peptide fragment representing the DNA-binding domain of filamentous virus Pf3 coat protein.

Raman spectra have been measured of a nonapeptide which has an amino acid sequence identical to that of the C-terminal region of the major coat protein subunit of filamentous bacteriophage Pf3. The peptide shows a strong tendency to form a beta-sheet structure in aqueous solution. The beta-sheet formation is significantly promoted by complexation with single-stranded DNA but not with double-stranded DNA. It is suggested that the C-terminal region of the Pf3 coat protein binds to the single-stranded DNA genome in the virion with a beta-sheet conformation, in sharp contrast with the alpha-helical binding in other filamentous bacteriophages.