Enzymatic Oligomerization of Bacteriophage P22 DNA and of Linear Simian Virus 40 DNA

Linear double-stranded molecules of the circularly permuted and terminally redundant DNA of Salmonella bacteriophage P22 have been converted to oligomeric products in the presence of polynucleotide ligase coded for by the coliphage T4. The reaction has been monitored by sucrose density-gradient centrifugation and electron microscopy. It goes slowly and gives yields of 30-40%. The products are mainly dimers and trimers, but higher oligomers are also present.DNA ligase extracted from uninfected Escherichia coli seems unable to perform a similar reaction, which is concluded to involve the fully base-paired termini. Linear double-stranded molecules of simian virus(SV) 40 DNA, produced by the action of the bacterial restriction endonuclease R(1), are oligomerized by either ligase; therefore, this reaction seems to involve single-stranded cohesive ends. No mixed products could be found when P22 DNA and linear SV 40 DNA were exposed together to the T4 ligase.