The Arrangements of Nucleotide Sequences in T2 and T5 DNA Molecules

The DNA molecule which is liberated from T2 or T4 bacteriophage is a linear duplex over most or all of its length. The genetic map of T4 (and presumably T2) is circular as shown by Streisinger, Edgar, and their collaborators, cited by Luria (1962, Ann. Rev. Microb. 16: 205–240). If genetic structure is a simple reflection of physical structure, then a problem arises: exactly how can a linear DNA molecule produce a circular genetic map? The suggestion has been made that the nucleotide message begins at different points in different molecules. This would mean that the sequences of nucleotides in the linear molecules liberated from an “isogenic” phage stock would be circular permutations of one another. Thus, markers most widely separated in one phage would be most closely linked in another and such a model might be able to account for the circular map. Dr. Irwin Rubenstein and I attempted...