A Protein Phosphatase 1 involved in correct nucleus positioning in trypanosomes

• RNAi medidated knock-down of PP1-3 leads to coordinated rearrangement of cellular organelles in the procyclic trypanosome.
• Nucleus shifted towards the posterior end of the cell.
• Lysosomal compartment is now mainly positioned towards the posterior end of the cell.
• Flagellum Attachment Zone is still constructed, allowing initiation of the cleavage furrow and cell division.

Reversible protein phosphorylation is a key regulator in intracellular functions. In the African trypanosome, Trypanosoma brucei, the serine–threonine phosphatase PP1-3, is localised in the cytoplasm. RNAi mediated knockdown of PP1-3 leads to a coordinated rearrangement of cellular organelles and compartments in the procyclic trypanosome. These parasites display their nucleus at the very posterior end of the cell. The kinetoplast is very close to the nucleus, and often located in a more anterior position. The lysosomal compartment, which in a normal procyclic cell is situated between nucleus and kinetoplast, is now positioned towards the anterior end of the cell. The Flagellum Attachment Zone, essential for cytokinesis, is still constructed, allowing initiation of the cleavage furrow and cell division. These adaptations allow dividing cells to distribute their organelles among the daughter cells and to proliferate normally. PP1-3 is therefore essential in conserving the intracellular organisation of the procyclic trypanosome cell.

In absence of PP1-3, the trypanosome nucleus is shifted towards the posterior end of the cell, leading to a coordinated rearrangement of cellular organelles.Figure optionsDownload high-quality image (153 K)Download as PowerPoint slide