INVESTIGADORES
ALVAREZ Vanina Eder
artículos
Título:
Centromere-associated topoisomerase activity in bloodstream form Trypanosoma brucei.
Autor/es:
OBADO SO; BOT C; ECHEVERRY MC; BAYONA JC; ALVAREZ VE; TAYLOR MC; KELLY JM
Revista:
NUCLEIC ACIDS RESEARCH
Editorial:
OXFORD UNIV PRESS
Referencias:
Año: 2011 vol. 39 p. 1023 - 1033
ISSN:
0305-1048
Resumen:
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.