Understanding the composition and function of the flagellar groove in bloodstream form Trypanosoma brucei

African Trypanosomiasis is a neglected tropical disease caused by the Trypanosoma brucei parasite and is transmitted by the bite of an infected tsetse fly. A characteristic feature of the bloodstream from of T. brucei is the flagellum, which is laterally attached to the side of the cell body and is not disassembled during the cell cycle. Instead, a new flagellum is formed alongside the old flagellum, with the distal tip of the new flagellum embedded within a cell body membrane invagination, called the groove. The groove is a highly mobile transmembrane junction and requires continuous remodelling of the subpellicular microtubule array as the new flagellum grows. To date, no molecular components of the groove are known, with the function of this structure undetermined. Moreover, in order to complete the cell cycle, the groove must resolve and release the new flagellum tip to initiate cytokinesis, with details of this process being unclear. We identified 13 proteins that localise to the flagellar groove using endogenous tagging of putative groove proteins identified through TrypTag. Five distinct patterns of localisation were observed. A deletion screen using CRISPR/Cas9 of the groove proteins releveled a selection of proteins involved in cytokinesis, such as CIF4, FAZ15 and FAZ16, as well as proteins involved in flagellum tip attachment, such as FCP4, Tb427.01.2710 and Tb427tmp.01.3030. These results have provided a knowledge base of the composition and function of the flagellar groove. Moreover, 3D electron microscopy techniques were used to understand the timing of groove resolution. We have demonstrated that the groove resolves post mitosis, when the new flagellum surpasses the old flagellum in length. We have also determined that two evolutionarily related trypanosomatids to T. brucei, Trypanosoma vivax and Trypanosoma congolense, do not fully embed their new flagellum distal tip in a canonical groove.

Grantor dc:publisher

Oxford Brookes University

Year dc:date

2022

Author dc:creator

• Smithson, Laura

Contributors dc:contributor

• Vaughan, Susan
• Sunter, Jack

Statement dc:rights

• All rights reserved

Language dc:language

en

DOI dc:identifier

https://doi.org/10.24384/jgrr-yp06

OAI identifier oai:identifier

tle:bbaaa2ba-4eb2-43de-8cb4-898fa53ea4c5:d6bd9758-527a-46cd-bfe2-c433766e8fca:1