On the origin of oligomer forms of polyoma DNA

Polyoma virus DNA synthesized in the presence of puromycin or cycloheximide contains an increased proportion of oligomers and molecules having a reduced number of tertiary turns. When doses of inhibitors producing a sub-maximal effect are used, molecules with an anomalous tertiary structure are more frequent among the oligomers than among the monomers. It is suggested that protein synthesis inhibitors modify the balance of factors controlling the topological constraints imposed on replicating molecules. Hence, final closure of the chains upon completion of replication would result in the formation of a mature product with an altered tertiary structure which sometimes fails to segregate into two daughter molecules.