Sequence homologies between ribosomal and phage RNAs: A proposed molecular basis for RNA phage parasitism

An extensive nucleotide sequence homology between the 3′-end of the 16 S ribosomal RNA and segments of bacteriophage MS2 or Qβ RNA is described. In addition, a notable sequence homology of coliphage RNAs with several other segments of ribosomal RNA is shown. The role of bacterial proteins in the recognition of phage RNA, and the resemblance of phage and host RNAs as the molecular basis of RNA phage parasitism is discussed.The problem of quantifying the degree of homology is discussed in the Appendix with a preliminary attempt towards a solution. A relative measure of homology is described, and used to analyze statistically the data obtained.