Degradation of linear DNA by a strand-specific exonuclease activity in Xenopus laevis oocytes.

AUTOR(ES)

Maryon, E

RESUMO

Linear DNA injected into Xenopus laevis oocyte nuclei recombines with high efficiency if homologous sequences are present at overlapping molecular ends. We found that injected linear DNA was degraded by a 5'----3' strand-specific exonuclease activity during incubation in the oocyte nucleus to leave a heterogeneous population of 3'-tailed molecules. Decreasing the concentration of DNA injected increased the heterogeneity and the average rate of degradation. The 3' tails created were relatively stable; among molecules persisting after overnight incubation, many had 3' tails intact to within 10 bases of the original ends. DNA molecules that were efficient substrates for homologous recombination in oocytes were also partially degraded, leaving 3' tails. We found no evidence for other potent nuclease activities. If molecules with recessed 3'-OH ends were injected, endogenous polymerase efficiently resynthesized complementary strands before degradation of the 5' tails occurred. 3'-tailed molecules are plausible intermediates in the initiation of homologous recombination events in Xenopus oocyte nuclei.

Documentos Relacionados

• AFM characterization of single strand-specific endonuclease activity on linear DNA
• DNA-relaxing activity and endonuclease activity in Xenopus laevis oocytes.
• Efficient homologous recombination of linear DNA substrates after injection into Xenopus laevis oocytes.
• mRNA- and DNA-directed synthesis of herpes simplex virus-coded exonuclease in Xenopus laevis oocytes.
• A strand-specific endonucleolytic activity with DNA site preference for cleavage in Chlamydia trachomatis.