Rat liver DNA ligases. Catalytic properties of a novel form of DNA ligase.
A novel form of rat liver DNA ligase (molecular mass 100 kDa) can be differentiated from DNA ligase I by several biochemical parameters. It is a more heat-labile enzyme and unable to join blunt-ended DNA, even in the presence of poly(ethylene glycol) concentrations which stimulate such joining by DNA ligase I and T4 DNA ligase. It also lacks the AMP-dependent nicking/closing reaction, which is a property of all other DNA ligases tested so far, including DNA ligase I from rat liver. Both rat liver DNA ligases were inhibited by deoxyadenosinetriphosphate, however this inhibition was competitive with respect to ATP, for DNA ligase I (Ki 22 microM) and non-competitive for the 100-kDa DNA ligase (Ki 170 microM). These results support the idea that, when compared with other DNA ligases, the novel form of DNA ligase has a unique AMP-binding site, may have an absolute requirement for single-strand breaks and, furthermore, may have an altered reaction mechanism to that which is conserved from bacteriophage to mammalian DNA ligase I.
Elder
R H
RH
UPR 272-CNRS, Institut de Recherches Scientifiques sur le Cancer, Villejuif, France.
Montecucco
A
A
Ciarrocchi
G
G
Rossignol
J M
JM
D000249:Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D004247:DNA / Q000378:metabolism; D011088:DNA Ligases / Q000378:metabolism*; D003838:Deoxyadenine Nucleotides / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D008099:Liver / Q000201:enzymology*; D051381:Rats; D013873:Thionucleotides / Q000378:metabolism
D003838:Deoxyadenine Nucleotides; D013873:Thionucleotides; C017817:adenosine 5'-(1-thio)triphosphate; D000249:Adenosine Monophosphate; D004247:DNA; D011088:DNA Ligases; C026600:2'-deoxyadenosine triphosphate