Two flagellar BAR domain proteins in Trypanosoma brucei with stage-specific regulation.

Zdenka Cicova,Mario Dejung,Steffen Hanselmann,Tomas Skalicky,Falk Butter,Brooke Morriswood,Christian J Janzen,Nicole Eisenhuth,Luisa M Figueiredo

doi:10.1038/srep35826

Abstract

Trypanosomes are masters of adaptation to different host environments during their complex life cycle. Large-scale proteomic approaches provide information on changes at the cellular level, and in a systematic way. However, detailed work on single components is necessary to understand the adaptation mechanisms on a molecular level. Here, we have performed a detailed characterization of a bloodstream form (BSF) stage-specific putative flagellar host adaptation factor Tb927.11.2400, identified previously in a SILAC-based comparative proteome study. Tb927.11.2400 shares 38% amino acid identity with TbFlabarin (Tb927.11.2410), a procyclic form (PCF) stage-specific flagellar BAR domain protein. We named Tb927.11.2400 TbFlabarin-like (TbFlabarinL), and demonstrate that it originates from a gene duplication event, which occurred in the African trypanosomes. TbFlabarinL is not essential for the growth of the parasites under cell culture conditions and it is dispensable for developmental differentiation from BSF to the PCF in vitro. We generated TbFlabarinL-specific antibodies, and showed that it localizes in the flagellum. Co-immunoprecipitation experiments together with a biochemical cell fractionation suggest a dual association of TbFlabarinL with the flagellar membrane and the components of the paraflagellar rod.

Highlights

We focused on a well-investigated structure that is highly adapted to different host environments: the trypanosome flagellum
We showed that TbFlabarinL is not essential for the growth of the parasite under cell culture conditions and that it is dispensable for developmental differentiation of trypanosomes
Predicted structural models[42] of both TbFlabarin and TbFlabarinL feature a triple helix coiled coil architecture (Fig. 1B). Such a structure is characteristic of BAR proteins and enables formation of banana-shaped homo- or heterodimers known for their membrane curvature generation

Summary

Introduction

While still attached to the salivary gland surface, trypanosomes acquire the VSG coat and mature into metacyclics These cells are preadapted for transfer to and life in the mammalian host when the fly takes a blood meal and completes the life cycle of the parasite[8]. In addition to the comparison of transcript abundance in PCF and BSF9, the transcriptome of differentiating parasites has been analyzed[10,11] These studies provided many insights into the adaptation machinery of trypanosomes but there are certain limitations to transcriptome-based approaches. Stable isotope labeling (SILAC) was used to quantitatively compare the proteomes of BSF and PCF, which elucidated many new components of the machinery for adaptation to the insect and mammalian hosts[16,17,18]. We focused on a well-investigated structure that is highly adapted to different host environments: the trypanosome flagellum

Methods

Results

Conclusion