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J Cell Sci. 2014 Nov 15;127(Pt 22):4846-56. doi: 10.1242/jcs.148015. Epub 2014 Sep 12.

The bi-lobe-associated LRRP1 regulates Ran activity in Trypanosoma brucei.

Author information

1
Department of Biological Sciences, Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, S1A #06-04, Singapore 117543, Singapore.
2
University of Texas Medical School.
3
Singapore Mechanobiology Institute, National University of Singapore, T-Lab, #10-01, 5A Engineering Drive 1, Singapore 117411, Singapore.
4
Department of Biological Sciences, Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, S1A #06-04, Singapore 117543, Singapore dbshyc@nus.edu.sg.

Abstract

Cilia and flagella are conserved eukaryotic organelles important for motility and sensory. The RanGTPase, best known for nucleocytoplasmic transport functions, may also play a role in protein trafficking into the specialized flagellar/ciliary compartments, although the regulatory mechanisms controlling Ran activity at the flagellum remain unclear. The unicellular parasite Trypanosoma brucei contains a single flagellum necessary for cell movement, division and morphogenesis. Correct flagellum functions require flagellar attachment to the cell body, which is mediated by a specialized flagellum attachment zone (FAZ) complex that is assembled together with the flagellum during the cell cycle. We have previously identified the leucine-rich-repeat protein 1 LRRP1 on a bi-lobe structure at the proximal base of flagellum and FAZ. LRRP1 is essential for bi-lobe and FAZ biogenesis, consequently affecting flagellum-driven cell motility and division. Here, we show that LRRP1 forms a complex with Ran and a Ran-binding protein, and regulates Ran-GTP hydrolysis in T. brucei. In addition to mitotic inhibition, depletion of Ran inhibits FAZ assembly in T. brucei, supporting the presence of a conserved mechanism that involves Ran in the regulation of flagellum functions in an early divergent eukaryote.

KEYWORDS:

Bi-lobe; Flagellum; LRRP1; Ran; RanBP

PMID:
25217630
DOI:
10.1242/jcs.148015
[Indexed for MEDLINE]
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