Dysfunction of chromosomal loop attachment sites: illegitimate recombination linked to matrix association regions and topoisomerase II.
AUTOR(ES)
Sperry, A O
RESUMO
A family of A + T-rich sequences termed MARs ("matrix association regions") mediate chromosomal loop attachment. Here we demonstrate that several MARs both specifically bind and contain multiple sites of cleavage by topoisomerase II, a major protein of the mitotic chromosomal scaffold. Interestingly, "hotspots" of enzyme cutting occur within the MAR of the mouse immunoglobulin kappa-chain gene at the breakpoint of a previously described chromosomal translocation. Since topoisomerase II can mediate illegitimate recombination in prokaryotes, we explored further the possibility that MARs might be targets for this process in eukaryotes. We found that a MAR had been deleted from one of the two rabbit immunoglobulin kappa-chain genes and that MARs reside next to a long interspersed repetitive element within the recombination junction of a human ring chromosome 21. These results, taken together with other accounts of nonhomologous recombination, lead to the proposal that a dysfunction of MARs is illegitimate recombination.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=297650Documentos Relacionados
- Identification within the simian virus 40 genome of a chromosomal loop attachment site that contains topoisomerase II cleavage sites.
- Illegitimate recombination mediated by calf thymus DNA topoisomerase II in vitro.
- Structural Domains and Matrix Attachment Regions along Colinear Chromosomal Segments of Maize and Sorghum
- Sequence specificity of illegitimate plasmid recombination in Bacillus subtilis: possible recognition sites for DNA topoisomerase I.
- The recognition of DNA cleavage sites by porcine spleen topoisomerase II.