Tandem Repeat Recombination Induced by Replication Fork Defects in Escherichia coli Requires a Novel Factor, RadC

Corresponding author: Susan T. Lovett, Rosenstiel Basic Medical Sciences Center MS029, Brandeis University, Waltham, MA 02454-9110., lovett{at}hydra.rose.brandeis.edu (E-mail)

Communicating editor: R. MAURER

DnaB is the helicase associated with the DNA polymerase III replication fork in Escherichia coli. Previously we observed that the dnaB107(ts) mutation, at its permissive temperature, greatly stimulated deletion events at chromosomal tandem repeats. This stimulation required recA, which suggests a recombinational mechanism. In this article we examine the genetic dependence of recombination stimulated by the dnaB107 mutation. Gap repair genes recF, recO, and recR were not required. Mutations in recB, required for double-strand break repair, and in ruvC, the Holliday junction resolvase gene, were synthetically lethal with dnaB107, causing enhanced temperature sensitivity. The hyperdeletion phenotype of dnaB107 was semidominant, and in dnaB107/dnaB⁺ heterozygotes recB was partially required for enhanced deletion, whereas ruvC was not. We believe that dnaB107 causes the stalling of replication forks, which may become broken and require repair. Misalignment of repeated sequences during RecBCD-mediated repair may account for most, but not all, of deletion stimulated by dnaB107. To our surprise, the radC gene, like recA, was required for virtually all recombination stimulated by dnaB107. The biochemical function of RadC is unknown, but is reported to be required for growth-medium-dependent repair of DNA strand breaks. Our results suggest that RadC functions specifically in recombinational repair that is associated with the replication fork.

This article has been cited by other articles:

				A. D. S. Cameron and R. J. Redfield Non-canonical CRP sites control competence regulons in Escherichia coli and many other {gamma}-proteobacteria Nucleic Acids Res., November 6, 2006; 34(20): 6001 - 6014. [Abstract] [Full Text] [PDF]

				S. T. Lovett, R. L. Hurley, V. A. Sutera Jr., R. H. Aubuchon, and M. A. Lebedeva Crossing Over Between Regions of Limited Homology in Escherichia coli: RecA-Dependent and RecA-Independent Pathways Genetics, March 1, 2002; 160(3): 851 - 859. [Abstract] [Full Text] [PDF]

				M. Dziejman, E. Balon, D. Boyd, C. M. Fraser, J. F. Heidelberg, and J. J. Mekalanos Comparative genomic analysis of Vibrio cholerae: Genes that correlate with cholera endemic and pandemic disease PNAS, January 24, 2002; (2002) 42667999. [Abstract] [Full Text] [PDF]

				P. McGlynn and R. G. Lloyd Action of RuvAB at Replication Fork Structures J. Biol. Chem., November 2, 2001; 276(45): 41938 - 41944. [Abstract] [Full Text] [PDF]

				M. M. Cox Historical overview: Searching for replication help in all of the rec places PNAS, July 17, 2001; 98(15): 8173 - 8180. [Abstract] [Full Text] [PDF]

				A. Kuzminov DNA replication meets genetic exchange: Chromosomal damage and its repair by homologous recombination PNAS, July 17, 2001; 98(15): 8461 - 8468. [Abstract] [Full Text] [PDF]

				M.-J. Lombardo and S. M. Rosenberg radC102 of Escherichia coli Is an Allele of recG J. Bacteriol., November 15, 2000; 182(22): 6287 - 6291. [Abstract] [Full Text]

				A. J. Welcker, J. de Montigny, S. Potier, and J.-L. Souciet Involvement of Very Short DNA Tandem Repeats and the Influence of the RAD52 Gene on the Occurrence of Deletions in Saccharomyces cerevisiae Genetics, October 1, 2000; 156(2): 549 - 557. [Abstract] [Full Text]

				R. Rothstein, B. Michel, and S. Gangloff Replication fork pausing and recombination or "gimme a break" Genes & Dev., January 1, 2000; 14(1): 1 - 10. [Full Text]

				A. Kuzminov Recombinational Repair of DNA Damage in Escherichia coli and Bacteriophage lambda Microbiol. Mol. Biol. Rev., December 1, 1999; 63(4): 751 - 813. [Abstract] [Full Text] [PDF]

				M. B. Avison, R. E. Horton, T. R. Walsh, and P. M. Bennett Escherichia coli CreBC Is a Global Regulator of Gene Expression That Responds to Growth in Minimal Media J. Biol. Chem., July 13, 2001; 276(29): 26955 - 26961. [Abstract] [Full Text] [PDF]

				M. Dziejman, E. Balon, D. Boyd, C. M. Fraser, J. F. Heidelberg, and J. J. Mekalanos Comparative genomic analysis of Vibrio cholerae: Genes that correlate with cholera endemic and pandemic disease PNAS, February 5, 2002; 99(3): 1556 - 1561. [Abstract] [Full Text] [PDF]