Studies on the mechanism of replication of adenovirus DNA: V. The Location of Termini of Replication

Abstract

The location of the termination sites of replication of adenovirus type 5 DNA has been determined by restriction enzyme analysis of the radioactivity distribution in newly synthesized pulse-labeled mature DNA molecules according to the procedure of Danna and Nathans (1972, Proc. Nat. Acad. Sci. USA 69, 3097–3100) . Fragmentation of newly completed molecules was achieved by cleavage with endo R. Hind III or endo R. Hsu I. These enzymes cleave adenovirus type 5 DNA into 10 fragments which map in the order G, E, C, H, J, D, A, B, F, I. Termination sites of replication were detected at the two molecular ends of the viral genome (fragments G and I). Only one of the two complementary strands at each termination site was labeled. The results indicate that the synthesis of the viral H-strand (the strand with the higher buoyant density in alkaline CsCl) starts at the right-hand end and terminates at the left-hand end of the molecule, while the L-strand is synthesized in the opposite direction, which supports a displacement type of replication.