Eukaryotic topoisomerase II cleavage of parallel stranded DNA tetraplexes

I. K. Chung, V. B. Mehta, J. R. Spitzner, M. T. Muller

Research output: Contribution to journalArticle

43 Citations (Scopus)


A guanine-rich single-stranded DNA from the human immunoglobulin switch region was shown by Sen and Gilbert [Nature, (1988) 334, 364-366] to be able to self-associate to form a stable four-stranded parallel DNA structure. Topoisomerase II did not cleave the single-stranded DNA molecule. Surprisingly, the enzyme did cleave the same DNA sequence when it was annealed into the four-stranded structure. The two cleavage sites observed were the same as those found when this DNA molecule was paired with a complementary molecule to create a normal B-DNA duplex. These cleavages were shown to be protein-linked and reversible by the addition of salt, suggesting a normal topolsomerase II reaction mechanism. In addition, an eight-stranded DNA molecule created by the association of a complementary oligonucleotide with the four-stranded structure was also cleaved by topolsomerase II despite being resistant to restriction endonuclease digestion. These results suggest that a single strand of DNA may possess the sequence Information to direct topoisomerase II to a binding site, but the site must be base paired in a proper manner to do so. This demonstration of the ability of a four-stranded DNA molecule to be a substrate for an enzyme further suggests that these DNA structures may be present in cells.

Original languageEnglish
Pages (from-to)1973-1977
Number of pages5
JournalNucleic acids research
Issue number8
Publication statusPublished - 1992 Apr 25

All Science Journal Classification (ASJC) codes

  • Genetics

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