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Endonuclease activity from tobacco nuclei specific for ultraviolet radiation‐damaged DNA
Author(s) -
Murphy Terence M.,
Martin Charles P.,
Kami James
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb01750.x
Subject(s) - pyrimidine dimer , endonuclease , photolyase , dna , divalent , chemistry , escherichia coli , microbiology and biotechnology , restriction enzyme , biochemistry , biology , dna damage , dna repair , organic chemistry , gene
Endonuclease activity specific for UV damaged DNA was isolated from tobacco leaf nuclei and detected by relaxation of supercoiled pUC 19 plasmid DNA. The activity did not require divalent cations or ATP. It acted on photoproducts induced by as little as 24 J m −2 of UV‐C (primarily 254 nm) radiation. but not on photoproducts produced by UV‐B (290–320 nm) radiation in the presence of acetophenone and a N 2 atmosphere or by UV‐A (320–400 nm) radiation in the presence of 4′‐methoxy‐methyltrioxsalen in a N 2 atmosphere and not on the products of OsO 4 oxidation of the DNA. Using end‐labeled DNA of defined sequence, it was possible to identify sites in UV‐C‐irradiated DNA that were cut by the endonuclease preparation: most sites were assocrated with pyrimidine pairs. Cleavage by the tobacco endonuclease was not eliminated by treatment with Escherichia coli photolyase and light, suggesting that the endonuclease did not recognize cyclobutadipyrimidines.