Centromere-associated topoisomerase activity in bloodstream form Trypanosoma brucei

Nucleic Acids Res. 2011 Feb;39(3):1023-33. doi: 10.1093/nar/gkq839. Epub 2010 Sep 22.

Abstract

Topoisomerase-II accumulates at centromeres during prometaphase, where it resolves the DNA catenations that represent the last link between sister chromatids. Previously, using approaches including etoposide-mediated topoisomerase-II cleavage, we mapped centromeric domains in trypanosomes, early branching eukaryotes in which chromosome segregation is poorly understood. Here, we show that in bloodstream form Trypanosoma brucei, RNAi-mediated depletion of topoisomerase-IIα, but not topoisomerase-IIβ, results in the abolition of centromere-localized activity and is lethal. Both phenotypes can be rescued by expression of the corresponding enzyme from T. cruzi. Therefore, processes which govern centromere-specific topoisomerase-II accumulation/activation have been functionally conserved within trypanosomes, despite the long evolutionary separation of these species and differences in centromeric DNA organization. The variable carboxyl terminal region of topoisomerase-II has a major role in regulating biological function. We therefore generated T. brucei lines expressing T. cruzi topoisomerase-II truncated at the carboxyl terminus and examined activity at centromeres after the RNAi-mediated depletion of the endogenous enzyme. A region necessary for nuclear localization was delineated to six residues. In other organisms, sumoylation of topoisomerase-II has been shown to be necessary for regulated chromosome segregation. Evidence that we present here suggests that sumoylation of the T. brucei enzyme is not required for centromere-specific cleavage activity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antigens, Neoplasm / chemistry
  • Antigens, Neoplasm / metabolism*
  • Centromere / enzymology*
  • DNA Cleavage
  • DNA Topoisomerases, Type II / chemistry
  • DNA Topoisomerases, Type II / metabolism*
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Molecular Sequence Data
  • RNA Interference
  • Sumoylation
  • Trypanosoma brucei brucei / enzymology*
  • Trypanosoma brucei brucei / genetics
  • Trypanosoma brucei brucei / growth & development
  • Trypanosoma cruzi / enzymology

Substances

  • Antigens, Neoplasm
  • DNA-Binding Proteins
  • DNA Topoisomerases, Type II