Authors

A Trenaman²; S Hutchinson¹; L Glover¹; D Horn²;  ¹ Institut Pasteur, France;  ² University of Dundee

Discussion

We ran an RNAi screen in bloodstream form T. brucei that implicated the RNA-binding proteins, ZC3H39 and ZC3H40 in variant surface glycoprotein (VSG) gene silencing. Knockdown of either protein disrupted VSG silencing as determined by western blotting, flow-cytometry and RNA-seq. The presence of a cytoplasmic ZC3H39/40 complex in T. brucei was supported by immunofluorescence co-localisation, co-destabilisation and co-immunoprecipitation. A CLIP-seq experiment, surprisingly, identified transcripts encoding multiple components of the electron transport chain, including those for cytochrome oxidase and the F-ATPase. Consistent with this association, these same transcripts were down-regulated in ZC3H39/40 knockdowns as determined by RNA-seq and by stable isotope labelling in cell culture followed by mass-spectrometry and proteomic profiling. Notably, this regulation was only observed in bloodstream form parasites following ZC3H40 knockdown. Thus, we report an RNA-binding complex that controls the expression of electron transport chain components in T. brucei. Our findings also establish an intriguing link between an electron transport chain regulome and VSG expression control.