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Eukaryotic Cell, September 2008, p. 1582-1590, Vol. 7, No. 9
1535-9778/08/$08.00+0 doi:10.1128/EC.00150-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158-2280
Received 30 April 2008/ Accepted 4 July 2008
Trypanosoma brucei, the etiologic agent of African sleeping sickness, divides into insect (procyclic) and bloodstream forms. These two forms are subject to distinct cell cycle regulations, with cytokinesis controlled primarily by basal body/kinetoplast segregation in the procyclic form but by mitosis in the bloodstream form. Polo-like kinases (PLKs), known to play essential roles in regulating both mitosis and cytokinesis among eukaryotes, have a homologue in T. brucei, TbPLK, which regulates only cytokinesis. In our previous study, overexpressed triply hemagglutinin-tagged TbPLK (TbPLK-3HA) in the procyclic form localized to a mid-dorsal point and the anterior tip of the cell along the flagellum attachment zone (FAZ). In our current study, TbPLK-3HA expressed at the endogenous level was identified at the same dorsal location of both procyclic and bloodstream forms, albeit it was no longer detectable at the anterior tip of the cell. Endogenously expressed TbPLK fused with an enhanced yellow fluorescent protein (EYFP) localized to the same dorsal location along the FAZs in living procyclic and bloodstream cells. Fluorescence-activated cell sorter analysis of hydroxyurea-synchronized procyclic cells revealed that TbPLK-EYFP emerges during S phase, persists through G2/M phase, and vanishes in G1 phase. An indicated TbPLK-EYFP association with the FAZs of G2/M cells may thus represent a timely localization to a potential initiation site of cytokinesis, which agrees with the recognized role of TbPLK in cytokinetic initiation.
Published ahead of print on 11 July 2008.
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