The trypanosome-specific protein CIF3 cooperates with the CIF1 protein to promote cytokinesis in Trypanosoma brucei

Abstract

Cytokinesis, the terminal step in cell division, in the protist human pathogen occurs along the longitudinal axis from the anterior tip of the new flagellum attachment zone (FAZ) toward the posterior cell tip. This process is regulated by a signaling cascade composed of the Polo-like kinase homolog TbPLK, the Aurora B kinase homolog TbAUK1, and the trypanosome-specific CIF1-CIF2 protein complex. However, the regulatory mechanism and the signaling pathway for this unusual mode of cytokinesis remain poorly understood. Here, we report another trypanosome-specific protein assembly, the CIF1-CIF3 complex, and its essential role in cytokinesis initiation. Through biochemical and genetic approaches, we demonstrate that CIF3 interacts with CIF1 in a TbPLK-dependent manner and maintains CIF1 localization at the new FAZ tip. Conversely, CIF1 maintains CIF3 stability at the new FAZ tip. We further show that TbPLK is required for CIF3 localization and that CIF3 is necessary for targeting TbAUK1 to the new FAZ tip during anaphase. These results suggest that two trypanosome-specific CIF1-containing protein complexes cooperate with the evolutionarily conserved Polo-like kinase and Aurora B kinase to promote cytokinesis in.

The CIF1 protein is a master orchestrator of trypanosome cytokinesis that recruits several cytokinesis regulators to the cytokinesis initiation site

“…Our previous proximity biotin identification (BioID) using CIF1 fused with a C-terminal BirA* as the bait identified 160 proteins as potential CIF1-associated partners (13), but the majority of them have not been validated and functionally characterized. We recently identified CIF3 as a binding partner of CIF1 (14), but CIF3 was not detected by CIF1 BioID, suggesting that certain CIF1-associated proteins may have been missed in our previous BioID experiments, potentially because of interference of the C-terminal BirA* tag. Therefore, we carried out new BioID experiments using CIF1 fused with an N-terminal BirA* as the bait and identified a total of 305 potential CIF1-associated proteins.…”

“…Among the 52 CIF1-associated proteins, five proteins localize to the new FAZ tip, including CIF2, FAZ18 (13), KPP1 (16), and two subunits of katanin, KAT60a and KAT80 (18). Three proteins localize to the new FAZ tip and the cleavage furrow, including CIF3 (14), an orphan kinesin (Tb927.8.4950) that was recently named KLIF (kinesin localized at ingressing furrow) (19), and a G 2 /M-enriched protein (Tb927.10.870) (20) we named FRW1 (furrow 1). Seven proteins localize to both the new and old FAZ tips, including four known FAZ tip proteins (TbSAS-4 (33), FAZ11, FAZ14, and FAZ20 (13)) and three new proteins named FAZ21 (Tb927.7.5240), FAZ24 (Tb927.10.…”

“…Subsequent identification of CIF1 as an essential cytokinesis regulator bridging TbPLK and TbAUK1 unveiled the mechanistic role of TbPLK in cytokinesis initiation and delineated a novel cytokinesis signaling pathway from TbPLK through CIF1 to TbAUK1 (12). CIF1 forms two separate protein complexes with two trypanosome-specific proteins, CIF2 (13) and CIF3 (14). The CIF1-CIF2 complex appears to function during S phase (13), and CIF1 is required for recruiting CIF2 to the new FAZ tip (15).…”

“…The CIF1-CIF2 complex appears to function during S phase (13), and CIF1 is required for recruiting CIF2 to the new FAZ tip (15). The CIF1-CIF3 complex likely acts from G 2 phase to cytokinesis, and the two protein subunits exert distinct effects on each other, with CIF1 maintaining CIF3 stability and CIF3 maintaining CIF1 localization (14). These studies built the framework for delineating the cytokinesis regulatory pathway and in-depth understanding of the mechanism of cytokinesis in T. brucei.…”

High-resolution linkage and quantitative trait locus mapping using an interspecific cross between Argopecten irradians irradians (♀) and A. purpuratus (♂)

“…Despite that the gaps in genomic assembly may limit identification of the potential causal genes within the QTL, growth-related genes, including SPR, Trip13, and KIF13B were recognized within the loose window of this QTL (Supplementary Table S2). These genes are involved in the control of reproductive behaviors (Bath et al 2017;Yapici et al 2008), gamete generation (Li and Schimenti 2007), and cytokinesis (Kurasawa et al 2018;Venkateswarlu et al 2005). The list of candidate genes and SNPs associated with traits supplies potential targets in the future selective breeding programs to improve scallop aquaculture production, but more validation work is still needed in a broader population.…”