Chromosome replication is one of the most crucial events in the cell cycle of Escherichia coli, and it is regulated at the initiation step. The initiation occurs at a unique site on the chromosome termed oriC which must be activated by several interacting proteins. The initiation event also requires RNA and protein synthesis. The biochemical nature of the protein synthesis requirement is not understood. Under certain circumstances, E. coli exhibits altered modes of DNA replication. These are constitutive stable DNA replication (cSDR) seen in rnh mutants which are devoid of ribonuclease H and induced stable DNA replication (iSDR) seen during the SOS response. Unlike normal replication, both modes of replication can be repeatedly initiated without concomitant protein synthesis. cSDR is initiated from a new set of origins )termed oriKs) other than oriC, and requires RNA synthesis. On the other hand, iSDR is initiated at two origins (termed oriMs) that are different from oriKs and from oriC. The initiation at oriMs requires neither protein synthesis nor RNA synthesis. This project is focused on the characterization of these two alternative DNA replication systems which are normally repressed but can be activated by genetic stress such as damage to DNA and a mutation in the rnh gene. The experiments are proposed: 1. To clone and characterize several oriK sites which are active only in rnh mutants; 2. To characterize the DNA-damage inducible origins of replication, oriMs. 3. To develope an in vitro DNA replication system to study the mechanism of the activation of oriMs by SOS-inducing signals. 4. To characterize a new type of Sdr mutants (sdrB) with the expectation that the study will lead to an insight into the nature of the protein synthesis requirements for initiation of chromosome replication at oriC.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM022092-16
Application #
3270930
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1978-12-01
Project End
1995-02-28
Budget Start
1991-03-01
Budget End
1992-02-29
Support Year
16
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of New Mexico
Department
Type
Schools of Arts and Sciences
DUNS #
829868723
City
Albuquerque
State
NM
Country
United States
Zip Code
87131
Kasahara, M; Clikeman, J A; Bates, D B et al. (2000) RecA protein-dependent R-loop formation in vitro. Genes Dev 14:360-5
Asai, T; Bates, D B; Boye, E et al. (1998) Are minichromosomes valid model systems for DNA replication control? Lessons learned from Escherichia coli. Mol Microbiol 29:671-5
Bates, D B; Boye, E; Asai, T et al. (1997) The absence of effect of gid or mioC transcription on the initiation of chromosomal replication in Escherichia coli. Proc Natl Acad Sci U S A 94:12497-502
Kogoma, T; Maldonado, R R (1997) DNA polymerase I in constitutive stable DNA replication in Escherichia coli. J Bacteriol 179:2109-15
Kogoma, T (1997) Stable DNA replication: interplay between DNA replication, homologous recombination, and transcription. Microbiol Mol Biol Rev 61:212-38
Hong, X; Cadwell, G W; Kogoma, T (1996) Activation of stable DNA replication in rapidly growing Escherichia coli at the time of entry to stationary phase. Mol Microbiol 21:953-61
Kogoma, T; Cadwell, G W; Barnard, K G et al. (1996) The DNA replication priming protein, PriA, is required for homologous recombination and double-strand break repair. J Bacteriol 178:1258-64
Bates, D B; Asai, T; Cao, Y et al. (1995) The DnaA box R4 in the minimal oriC is dispensable for initiation of Escherichia coli chromosome replication. Nucleic Acids Res 23:3119-25
Hong, X; Cadwell, G W; Kogoma, T (1995) Escherichia coli RecG and RecA proteins in R-loop formation. EMBO J 14:2385-92
Cao, Y; Kogoma, T (1995) The mechanism of recA polA lethality: suppression by RecA-independent recombination repair activated by the lexA(Def) mutation in Escherichia coli. Genetics 139:1483-94

Showing the most recent 10 out of 39 publications