Topoisomerase I action on the heterochromatic DNA from the brine shrimp Artemia franciscana: Studies in vivo and in vitro

D. Carettoni, N. Landsberger, E. Zagni, R. Benfante, G. Badaracco

Research output: Contribution to journalArticle

Abstract

The genomes of higher eukaryotes contain various amounts of tandem repeated DNA sequences (satellite DNA) typically located in the constitutive heterochromatin, the most highly condensed region of interphase chromosomes. We have previously demonstrated that an AluI DNA family of repeats is the major component of constitutive heterochromatin in the brine shrimp Artemia franciscana. The analysis of cloned heterochromatic fragments revealed that this repetitive DNA shows a stable curvature conferring a solenoidal geometry to the double helix. In this paper we provide evidence, using the antitumour drug camptothecin, that, in vivo, topoisomerase I cleaves heterochromatin with a frequency comparable with that observed in the whole genome. The analysis of the break sites shows that the enzyme cleaves heterochromatic DNA at specific sites characterized by a degenerate consensus sequence. Moreover the enzyme-mediated breaks have, in vitro, a degenerate consensus sequence similar to, but not identical with, the in vivo one. Some of these sites are influenced by the DNA flanking the heterochromatic insert, suggesting that structural variations could modify the enzyme specificity.

Original languageEnglish
Pages (from-to)623-629
Number of pages7
JournalBiochemical Journal
Volume299
Issue number3
Publication statusPublished - 1994

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Dolphins
Artemia
Type I DNA Topoisomerase
Heterochromatin
DNA
Consensus Sequence
Enzymes
Genes
Genome
Satellite DNA
Camptothecin
DNA sequences
Interphase
Chromosomes
Eukaryota
Antineoplastic Agents
Geometry
In Vitro Techniques
brine

ASJC Scopus subject areas

  • Biochemistry

Cite this

Carettoni, D., Landsberger, N., Zagni, E., Benfante, R., & Badaracco, G. (1994). Topoisomerase I action on the heterochromatic DNA from the brine shrimp Artemia franciscana: Studies in vivo and in vitro. Biochemical Journal, 299(3), 623-629.

Topoisomerase I action on the heterochromatic DNA from the brine shrimp Artemia franciscana : Studies in vivo and in vitro. / Carettoni, D.; Landsberger, N.; Zagni, E.; Benfante, R.; Badaracco, G.

In: Biochemical Journal, Vol. 299, No. 3, 1994, p. 623-629.

Research output: Contribution to journalArticle

Carettoni, D, Landsberger, N, Zagni, E, Benfante, R & Badaracco, G 1994, 'Topoisomerase I action on the heterochromatic DNA from the brine shrimp Artemia franciscana: Studies in vivo and in vitro', Biochemical Journal, vol. 299, no. 3, pp. 623-629.
Carettoni, D. ; Landsberger, N. ; Zagni, E. ; Benfante, R. ; Badaracco, G. / Topoisomerase I action on the heterochromatic DNA from the brine shrimp Artemia franciscana : Studies in vivo and in vitro. In: Biochemical Journal. 1994 ; Vol. 299, No. 3. pp. 623-629.
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