Repair of the Escherichia coli Chromosome after in vivo Scission by the EcoRi Endonuclease

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 86; no. 7; pp. 2281 - 2285
• Main Authors: Heitman, Joseph, Zinder, Norton D., Model, Peter
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.04.1989; National Acad Sciences
• Subjects: Alleles; Bacteriophages; Biological and medical sciences; Cell growth; Chromosomes; Chromosomes, Bacterial - physiology; Deoxyribonuclease EcoRI; DNA; DNA breaks; DNA Damage; DNA Repair; Escherichia coli; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Genetic SOS response; Genic rearrangement. Recombination. Transposable element; Genotype; Kinetics; Molecular and cellular biology; Molecular genetics; Mutation; Plasmids; Restriction Mapping; Rock cleavage; Enzyme; Endodeoxyribonuclease EcoRI; Escherichia coli; Enzymatic digestion; Bacteria; Chromosome; Repair; Escherichieae; Enterobacteriaceae
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.86.7.2281

We prepared a set of temperature-sensitive mutants of the EcoRI endonuclease. Under semipermissive conditions, Escherichia coli strains bearing these alleles form poorly growing colonies in which intracellular substrates are cleaved at EcoRI sites and the SOS DNA repair response is induced. Strains defective in SOS induction (lexA3 mutant) or SOS induction and recombination (recA56 and recB21 mutants) are not more sensitive to this in vivo DNA scission, whereas strains deficient in DNA ligase (lig4 and lig ts7 mutants) are extremely sensitive. We conclude that although DNA scission induces the SOS response, neither this induction nor recombination are required for repair. DNA ligase is necessary and may be sufficient to repair EcoRI-mediated DNA breaks in the E. coli chromosome.