Chlorella virus marburg topoisomerase II: High DNA cleavage activity as a characteristic of chlorella virus type II enzymes

Jennifer S. Dickey, Tae Jin Choi, James L. Van Etten, Neil Osheroff

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Although the formation of a covalent enzyme-cleaved DNA complex is a prerequisite for the essential functions of topoisomerase II, this reaction intermediate has the potential to destabilize the genome. Consequently, all known eukaryotic type II enzymes maintain this complex at a low steady-state level. Recently, however, a novel topoisomerase II was discovered in Paramecium bursaria chlorella virus-1 (PBCV-1) that has an exceptionally high DNA cleavage activity [Fortune et al. (2001) J. Biol. Chem. 276, 24401-24408]. If robust DNA cleavage is critical to the physiological functions of chlorella virus topoisomerase II, then this remarkable characteristic should be conserved throughout the viral family. Therefore, topoisomerase II from Chlorella virus Marburg-1 (CVM-1), a distant family member, was expressed in yeast, isolated, and characterized. CVM-1 topoisomerase II is 1058 amino acids in length, making it the smallest known type II enzyme. The viral topoisomerase II displayed a high DNA strand passage activity and a DNA cleavage activity that was ∼50-fold greater than that of human topoisomerase IIα. High DNA cleavage appeared to result from a greater rate of scission rather than promiscuous DNA site utilization, inordinately tight DNA binding, or diminished religation rates. Despite the fact that CVM-1 and PBCV-1 topoisomerase II share ∼67% amino acid sequence identity, the two enzymes displayed clear differences in their DNA cleavage specificity/site utilization. These findings suggest that robust DNA cleavage is intrinsic to the viral enzyme and imply that chlorella virus topoisomerase II plays a physiological role beyond the control of DNA topology.

Original languageEnglish (US)
Pages (from-to)3899-3908
Number of pages10
Issue number10
StatePublished - Mar 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'Chlorella virus marburg topoisomerase II: High DNA cleavage activity as a characteristic of chlorella virus type II enzymes'. Together they form a unique fingerprint.

Cite this