Identification of a Novel Base J Binding Protein Complex Involved in RNA Polymerase II Transcription Termination in Trypanosomes

Rudo Kieft; Yang Zhang; Alexandre P. Marand; Jose Dagoberto Moran; Robert Bridger; Lance Wells; Robert J. Schmitz; Robert Sabatini

LtPP1 is found to be stably associated in PJW/PP1 complex, possibly through its putative PP1-289 interacting protein, PNUTS. PNUTS is present in both the T. brucei and Leishmania complex and share a 290 conserved RVxF motif ( Fig 1C) . Moreover, a similar human PTW/PP1 complex suggests that PP1 confers 291 the complex phosphatase activity critical for its regulation in Pol II termination (2, 3, 53, 54). The apparent 292 lack of PP1 in the T. brucei complex is therefore surprising. To identify the TbPP1 component, we directly 293 tested two of the eight PP1 genes in T. brucei for interactions with the complex by co-IP. PP1-1 has the 294 highest sequence homology to the PP1 involved in termination in yeast and humans (51). PP1-7 has . CC-BY 4.0 International license is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/753004 doi: bioRxiv preprint 295 been identified in the nucleus of T. brucei (55). However, neither of these PP1 proteins associate with 296 TbPNUTS in the co-IP (S3C Fig). Alternatively, PP1 is not stably associated with the complex in T. brucei.