Investigating the role of CEP43 in paraflagellar rod assembly in Trypanosoma brucei

Nugawela, Aro and Urbaniak, Mick and McKean, Paul (2024) Investigating the role of CEP43 in paraflagellar rod assembly in Trypanosoma brucei. PhD thesis, Lancaster University.

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Abstract

Centrosomal protein 43 (CEP43) is basal body or centriolar protein conserved in flagellated and ciliated eukaryotes. Canonically, CEP43 functions in microtubule stabilization, patterning of asymmetric basal body auxiliary structures and the recruitment of the IFT-B complex. In the latter role, CEP43 works in concert with a conserved module of basal body or centriolar proteins, facilitating the anchoring of IFT-B and promoting ciliogenesis. Previously reported RNAi depletion of CEP43 in procyclic form T. brucei has established a causal link between loss of CEP43 and an inability to assemble the lineage-specific paraflagellar rod structure. The work presented in this thesis elaborates on the function of CEP43 in T. brucei. Data presented here identifies altered integration of PFR components into the flagellum compartment and PFR structure due to CEP43 depletion, and additionally highlights a novel malformation in PFR structure, characterised by partial polymerisation of disorganised PFR material into filamentous structures. Furthermore, the interrogations presented within this thesis have revealed an unusual IFT-defect arising from the depletion of CEP43, alongside preliminary insights into a PFR structural uniformity defect in flagella formed prior to CEP43RNAi induction. Finally, this thesis resolves the distribution of CEP43 protein at the basal body of T. brucei, characterising a structural asymmetry reminiscent of a horseshoe. This body of work provides new understanding of the function of CEP43 in T. brucei and raises the possibility that its asymmetric distribution at the basal body may align with its function in PFR assembly, patterning and IFT train movement.