Premium
5′ to 3′ Single Strand DNA Exonuclease Activity in a Preparation of Human Ku Protein
Author(s) -
Morozov Viktor E.,
Fuller Brian G.
Publication year - 1999
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/713803567
Subject(s) - exonuclease , helicase , nuclease , dna , chemistry , divalent , duplex (building) , recbcd , proofreading , klenow fragment , coding strand , enzyme , biochemistry , biophysics , dna polymerase , microbiology and biotechnology , biology , dna repair , polymerase , rna , gene , organic chemistry
We describe a novel 5′ to 3′ single‐strand exonuclease activity exhibited by a Ku preparation purified from a human cell line. The enzyme removes 5′ single‐strand extensions from duplex DNA molecules. The exonuclease and helicase activities respond reciprocally to changes in ATP concentrations: Nuclease activity is inhibited at the ATP concentrations that are optimal for the helicase. The exonuclease activity does not require divalent cations. The potential implications of the exonuclease activity findings for repair of double‐strand breaks and recombination processes are discussed.