Inhibition of Micrococcus luteus DNA topoisomerase I by UV photoproducts.
AUTOR(ES)
Pedrini, A M
RESUMO
The activity of Micrococcus luteus DNA topoisomerase I on UV-irradiated supercoiled DNA was studied under either processive or distributive reaction conditions. Changes in DNA structure caused by UV irradiation reduce the rate of DNA relaxation at very low concentration of photoproducts. Under processive conditions the inhibition of the topoisomerase I by photoproducts can be quantitated by measuring the amount of substrate left in the replicative form I band. The mode of action of DNA topoisomerase I was affected by the presence of photoproducts in the DNA substrate, although the ability of the enzyme to form a covalent complex with UV-irradiated supercoiled DNA was not changed. The inhibition of topoisomerase I by UV photoproducts has been compared to the effects of single-stranded DNA and UV-irradiated duplex linear DNA on the enzyme, and the results suggest that the inhibition by photoproducts is caused by changes in the conformation of the supercoil. Our findings indicate the possibility that DNA topoisomerase I plays a role in repair.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=393694Documentos Relacionados
- Sequence effect on incision by (A)BC excinuclease of 4NQO adducts and UV photoproducts.
- Inhibition of Micrococcus luteus DNA gyrase by norfloxacin and 10 other quinolone carboxylic acids.
- In Vitro Repair of UV-Irradiated Micrococcus luteus Bacteriophage N1 Transfecting DNA 1
- Utilization of DNA photolyase, pyrimidine dimer endonucleases, and alkali hydrolysis in the analysis of aberrant ABC excinuclease incisions adjacent to UV-induced DNA photoproducts.
- DNA-relaxing enzyme from Micrococcus luteus.