Studies on the Bacteriophage MS2

Abstract

The 5′‐terminal sequence of bacteriophage MS2 RNA was established up to position 125. The overlap with the ribosomal binding site for the A‐protein cistron indicates that the first initiating A‐U‐G codon starts at position 130. A characteristic secondary structure with a high amount of base‐pairing is proposed for this 5′‐terminal fragment. The existence of a symmetrical structure at the 3′‐end of the complementary minus strand can be deduced. It is suggested that the latter structure forms the basis of a specific three‐dimensional folding, which may serve as a recognition site for the viral RNA polymerase complex. Both structures bear some analogy to the cloverleaf model for tRNA, especially the one of the complementary strand. Not only does it end on… C‐C‐A, but the general outline of the secondary structure is also similar, except for the length of the loops and the presence of one extra loop.