Eukaryotic Cell doi:10.1128/EC.00150-08
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Polo-like kinase is expressed in S/G2/M-phase and associated with FAZ in both procyclic and bloodstream Trypanosoma brucei
Takashi Umeyama
and
Ching C. Wang*
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA 94158-2280
* To whom correspondence should be addressed. Email:
ccwang{at}cgl.ucsf.edu.
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Abstract |
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Trypanosoma brucei, the etiologic agent of African sleeping sickness, divides in the 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, 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, an over-expressed 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 to the same dorsal location of both procyclic and bloodstream forms, albeit 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 FAZ in living procyclic and bloodstream cells. FACS 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 FAZ 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.
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