Abstract
The parasitic protozoan Trypanosoma brucei contains two type III phosphatidylinositol 4-kinases (α and β). We have cloned the gene encoding the T. brucei type III phosphatidylinositol 4-kinase β (TbPI4KIII-β), expressed the protein in COS-7 cells, and confirmed that the protein catalyzes the phosphorylation of phosphatidylinositol. Depletion of TbPI4KIII-β in procyclic T. brucei by RNA interference (RNAi) resulted in inhibition of cell growth and a distorted cellular morphology. RNAi cells had a distorted Golgi apparatus, and lysosomal and flagellar pocket proteins were mislocalized. Ultrastructural analysis revealed the internal accumulation of a heterogeneous population of vesicles, abnormal positioning of organelles, and a loss of cell polarity. Scanning electron microcopy revealed a twisted phenotype, and dividing cells often exhibited a detached daughter flagellum and lacked a cleavage furrow. Cell cycle analysis confirmed that cells depleted of TbPI4KIII-β have a postmitotic cytokinesis block that occurs after a single round of mitosis, suggestive of a specific cell cycle block. In summary, TbPI4KIII-β is an essential protein in procyclic T. brucei, required for maintenance of Golgi structure, protein trafficking, normal cellular shape, and cytokinesis.
Original language | English (US) |
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Pages (from-to) | 1108-1118 |
Number of pages | 11 |
Journal | Eukaryotic Cell |
Volume | 6 |
Issue number | 7 |
DOIs | |
State | Published - Jul 2007 |
ASJC Scopus subject areas
- Microbiology
- Molecular Biology