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Endonuclease G: a (dG)n X (dC)n‐specific DNase from higher eukaryotes.
Author(s) -
RuizCarrillo A.,
Renaud J.
Publication year - 1987
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1987.tb04769.x
Subject(s) - biology , deoxyribonuclease i , endonuclease , deoxyribonucleases , microbiology and biotechnology , genetics , base sequence , dna
An endonuclease activity (termed endonuclease G) that selectively cleaves DNA at (dG)n X (dC)n tracts has been partially purified from immature chicken erythrocyte nuclei. Sites where n greater than or equal to 9 are cleaved in a manner that resembles types II and III restriction nucleases. The nicking rate of the G‐strand is 4‐ to 10‐fold higher than that of the C‐strand depending on the length of the (dG)n X (dC)n tract and/or nucleotide composition of the flanking sequences. Endonuclease G hydrolyzes (dG)24 X (dC)24 of supercoiled DNA in a bimodal way every 9‐11 nucleotides, the maxima in one strand corresponding to minima in the opposite, suggesting that it binds preferentially to one side of the double helix. The nuclease produces 5′ phosphomonoester ends and its activity is dependent on Mg2+ or Mn2+. The wide distribution and high relative activity of endonuclease G in a variety of tissues and species argues for a general role of the enzyme. The striking correlation between genetic instability and poly(dG) X poly(dC) tracts in DNA suggests that these sequences and endonuclease G are involved in recombination processes.