Dissection and Comparative Anatomy of the Origins of Replication of Lambdoid Phages (original) (raw)

1. D. D. Moore,
2. K. Denniston-Thompson*,
3. K. E. Kruger,
4. M. E. Furth†,
5. B. G. Williams‡,
6. D. L. Daniels, and
7. F. R. Blattner
8. University of Wisconsin, Department of Genetics, Madison, Wisconsin 53706; *National Cancer Institute, Bethesda, Maryland 20014; †MRC Laboratories, Cambridge, England; ‡Cetus Corporation, Emeryville, California 94608

Excerpt

Bacteriophage λ DNA replication begins at a unique origin region located near position 40,000 on the 50,000-bp-long λ DNA molecule. A map of this region is shown in Figure 1. Initiation leads to formation of a pair of replication forks which proceed in both directions away from the origin region.

Little is known about the molecular events leading to the formation of two forks, including the number, mechanism, location, and timing of deoxynucleotide chain initiations. Logically, there must be at least two initiation sites, S1 and S2, one for each strand. These might, in principle, have different mechanisms. Recent studies of small DNA phages (Kornberg, this volume) and of plasmids (Itoh and Tomizawa, this volume) have revealed a variety of possible mechanisms that could be used singly or in combination in the S1 and S2 initiations of λ.

Two specific hypotheses have been made for these initiations in λ. The...