DNA polymerase III holoenzyme (Pol1III holoenzyme), the major replicative polymerase of E. coli is isolated as a complex of at least eight polypeptides and can be reconstituted from purified preparations of subunits. Although individual functions of some of the subunits are still unknown, collectively they confer upon the pol1III holoenzyme special properties that distinguish it as a major replicative polymerase. It is extremely rapid in locating a primer, it hydrolyzes ATP to initiative extremely processive synthesis, has high catalytic efficiency and diffuses on duplex DNA to search for a primer terminus. In this proposal the specific aims are to study the diffusion properties of the enzyme on DNA, the mechanisms underlying rapid location of a primer terminus, the stoichiometry and spatial orientation of subunits within the enzyme and their interaction with a primer terminus. The ultimate aim of this program is a detailed molecular description of the events at the replication fork of a growing chromosome and a grasp of the basic principles that underlie them. Dr. O'Donnell has received excellent postdoctoral training with Kornberg and with Lehman, and is skilled in the techniques of biochemistry and molecular biology. He is well qualified to pursue the proposed research.
