Elements in abasic site recognition by the major human and Escherichia coli apurinic/apyrimidinic endonucleases.
AUTOR(ES)
Erzberger, J P
RESUMO
Sites of base loss in DNA arise spontaneously, are induced by damaging agents or are generated by DNA glycosylases. Repair of these potentially mutagenic or lethal lesions is carried out by apurinic/apyrimidinic (AP) endonucleases. To test current models of AP site recognition, we examined the effects of site-specific DNA structural modifications and an F266A mutation on incision and protein-DNA complex formation by the major human AP endonuclease, Ape. Changing the ring component of the abasic site from a neutral tetrahydrofuran (F) to a positively charged pyrrolidine had only a 4-fold effect on the binding capacity of Ape. A non-polar 4-methylindole base analog opposite F had a <2-fold effect on the incision activity of Ape and the human protein was unable to incise or specifically bind 'bulged' DNA substrates. Mutant Ape F266A protein complexed with F-containing DNA with only a 6-fold reduced affinity relative to wild-type protein. Similar studies are described using Escherichia coli AP endonucleases, exonuclease III and endonuclease IV. The results, in combination with previous findings, indicate that the ring structure of an AP site, the base opposite an AP site, the conformation of AP-DNA prior to protein binding and the F266 residue of Ape are not critical elements in targeted recognition by AP endonucleases.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=147600Documentos Relacionados
- Thermodynamic, kinetic and structural basis for recognition and repair of abasic sites in DNA by apurinic/apyrimidinic endonuclease from human placenta
- Total sequence decomposition distinguishes functional modules, "molegos" in apurinic/apyrimidinic endonucleases
- Apurinic/apyrimidinic endonucleases in repair of pyrimidine dimers and other lesions in DNA.
- Mechanism of incision by an apurinic/apyrimidinic endonuclease present in human placenta.
- Loss of an apurinic/apyrimidinic site endonuclease increases the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine to Escherichia coli.