Chinese hamster AP endonuclease operates by a two-metal ion assisted catalytic mechanism.
The APE1, an important mammalian AP endonuclease, is an essential enzyme in the base excision DNA repair pathway (BER). The number of metal ions involved directly in the catalysis remains controversial. Here we describe the metal ion titration experiments that demonstrate the requirement for two metal ions for the endonuclease activity of the Chinese hamster APE1. The titration with the non-activating metal ion La(3+) showed a biphasic behavior with activating and inhibitory effects of La(3+) in the range of 0-100 μM in the presence of 5 mM Mg(2+). Modeling of the enzyme-substrate/product complexes provided insight into the endonuclease activity and elucidated the nature of the crystal structures. Accordingly, we proposed a reaction scheme for the two-metal ion assisted catalysis of chAPE1 endonuclease activity.
Department of Chemistry, Bowling Green State University, 144 Overman Hall, Bowling Green, OH 43403, USA. dman@bgsu.edu
Mandula
M
Borjigin
Pablo
P
Arenaz
Boguslaw
B
Stec
D000818:Animals; D055162:Biocatalysis / Q000187:drug effects*; D020134:Catalytic Domain; D006224:Cricetinae; D003412:Cricetulus; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D008958:Models, Molecular
D007811:Lanthanum; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008274:Magnesium