From the flagellum attachment zone to the tripartite attachment complex - widespread cytoskeletal engagement of T. brucei KMP11.

KMP11 is a conserved kinetoplastid protein yet its precise localization and function remained unclear. Using immunofluorescence, ultrastructure expansion microscopy (U-ExM), and proteomics, we comprehensively analyzed KMP11 in procyclic Trypanosoma brucei. Besides confirming localization to the flagellum attachment zone (FAZ), we identify previously unknown localizations at the paraflagellar rod (PFR), flagellar connector (FC), microtubule quartet (MtQ) and flagellar pocket collar/hook complex (FPC/HC) region. We further show that the previously described basal body localization corresponds to the tripartite attachment complex (TAC). Proteomic analyses identify multiple cytoskeletal interactors, including the TAC component p197. Immunoprecipitation and U-ExM analyses demonstrate that KMP11 associates with the central α-helical domain of p197 from both T. brucei and Trypanosoma cruzi. Furthermore, KMP11 interactors overall display significantly elevated α-helical content. Together, our findings establish KMP11 as a component of a broad cytoskeletal interaction network in trypanosomes and we speculate that KMP11 preferentially associates with α-helical proteins.