Complete nucleotide sequence of the cohesive ends of bacteriophage P2 deoxyribonucleic acid.

At the ends of bacteriophage P2 DNA, the S’-terminated strands are 19 nucleotides longer than the 3’-terminated strands. The complete nucleotide sequence of the two cohesive ends of P2 DNA has been determined. This was accomplished by repair synthesis, using Escherichia coIi DNA polymerase and labeled deoxyribonucleoside triphosphates with or without a ribonucleoside triphosphate, followed by partial enzymatic digestions of the labeled segments and sequence analysis of the isolated oligonucleotides. Starting from the 5’ end of one cohesive end, the 19 nucleotides are in the sequence dpGpTpGpCpTpTpTpCpCpCpCpGpCpCpT’pCpGpCpC. The sequence from the other cohesive ends is exactly complementary to this one. The underlined bases differ from the sequence of the corresponding cohesive end of bacteriophage 186 DNA. Thus, DNA molecules from two related phages can form mixed dimers and help each other in infectivity assay even though the cohesive end sequences are not identical. The functional and thermodynamic significance of these findings is discussed.