The DNA of a cell presents the first line of control over metabolic and genetic processes. Replication of this repository of information is the primal biochemical act of cells. The goals of this proposal are to determine how this event occurs. Our focus will be on the function of DNA polymerases in E. coli. We will use biochemical and genetic means to analyze a mutation (pcbA) which permits by-pass of a replication block due to a defective DNA polymerase III through utilization of DNA polymerase I. We will investigate the biochemical mechanism of action of the pcbA mutation using in vitro complementation in a phage replication system. Characterization of the pcb gene will also require cloning, using complementation of temperature sensitivity in polCts mutants. Achieving this goal will permit biochemical analysis of the mutant gene and study of the gene product. The relief of replication blockade suggests that DNA polymerase III may be eliminated by mutagenesis. We will attempt to do that. We will also purify and characterize the DNA polymerase I arising as a reaction of suppression of the polAI amber mutation.
| Maki, H; Bryan, S K; Horiuchi, T et al. (1989) Suppression of dnaE nonsense mutations by pcbA1. J Bacteriol 171:3139-43 |
| Bryan, S; Chen, H; Sun, Y et al. (1988) Alternate pathways of DNA replication in Escherichia coli. Biochim Biophys Acta 951:249-54 |
| Bryan, S K; Moses, R E (1988) Sufficiency of the Klenow fragment for survival of polC(Ts) pcbA1 Escherichia coli at 43 degrees C. J Bacteriol 170:456-8 |
| Hagensee, M E; Timme, T L; Bryan, S K et al. (1987) DNA polymerase III of Escherichia coli is required for UV and ethyl methanesulfonate mutagenesis. Proc Natl Acad Sci U S A 84:4195-9 |
| Hagensee, M E; Bryan, S K; Moses, R E (1987) DNA polymerase III requirement for repair of DNA damage caused by methyl methanesulfonate and hydrogen peroxide. J Bacteriol 169:4608-13 |
| Hagensee, M E; Moses, R E (1986) Repair response of Escherichia coli to hydrogen peroxide DNA damage. J Bacteriol 168:1059-65 |
