Heitman J, Zinder N D, Model P
Rockefeller University, New York, N.Y. 10021.
Proc Natl Acad Sci U S A. 1989 Apr;86(7):2281-5. 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.
我们制备了一组EcoRI核酸内切酶的温度敏感突变体。在半允许条件下，携带这些等位基因的大肠杆菌菌株形成生长不良的菌落，其中细胞内底物在EcoRI位点被切割，并且诱导了SOS DNA修复反应。SOS诱导缺陷的菌株（lexA3突变体）或SOS诱导和重组缺陷的菌株（recA56和recB21突变体）对这种体内DNA断裂并不更敏感，而DNA连接酶缺陷的菌株（lig4和lig ts7突变体）则极其敏感。我们得出结论，虽然DNA断裂诱导了SOS反应，但修复既不需要这种诱导也不需要重组。DNA连接酶是必需的，并且可能足以修复大肠杆菌染色体中EcoRI介导的DNA断裂。
