Obado, Samson O; Bot, Christopher; Echeverry, Maria C; Bayona, Julio C; Alvarez, Vanina E; Taylor, Martin C; Kelly, John M; (2011) Centromere-associated topoisomerase activity in bloodstream form Trypanosoma brucei. Nucleic acids research, 39 (3). pp. 1023-1033. ISSN 0305-1048 DOI: https://doi.org/10.1093/nar/gkq839
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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.
Item Type | Article |
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Faculty and Department | Faculty of Infectious and Tropical Diseases > Department of Infection Biology |
Research Centre | Neglected Tropical Diseases Network |
PubMed ID | 20864447 |
ISI | 287257500028 |
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