Open AccessSubstrate Specificity of the Ultraviolet‐Endonuclease from Micrococcus luteus
Author(s) -
TOMILIN Nikolai V.,
PAVELTCHUK Elena B.,
MOSEVITSKAYA Tatyana V.
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10882.x
Subject(s) - ap site , endonuclease , pyrimidine dimer , micrococcus luteus , dna , ultraviolet light , biochemistry , microbiology and biotechnology , escherichia coli , enzyme , biology , chemistry , dna damage , photochemistry , gene
The ultraviolet‐endonuclease isolated from Micrococcus Iuteus, specific for pyrimidine dimers, is able to attack not only ultraviolet‐irradiated DNA (leading to 3′OH‐5′PO 4 single‐strand breaks) but also superhelical covalently‐closed circular DNA of phage λ damaged by heating at 70°C, pH 5.93. The number of endonuclease‐sensitive defects in the DNA corresponds to the number of alkailabile bonds (apurinic sites) induced by heating. Competition between ultraviolet‐induced lesions and apurinic, sites for ultraviolet‐endonuclease is demonstrated; the affinity of the enzyme for pyrimidine dimers is about three times that for apurinic sites. Both activities of the ultraviolet‐endonuclease are inactivated at 50 °C at the same rate. The ultraviolet‐endonuclease is able to reduce the infectious activity of depurinated λ DNA towards Ca 2+ ‐treated uvr + and uvr A Escherichia coli cells.