Trypanosoma brucei L11 Is Essential to Ribosome Biogenesis and Interacts with the Kinetoplastid-Specific Proteins P34 and P37

Abstract

Eukaryotic ribosome biogenesis is an essential cellular process involving tightly coordinated assembly of multiple rRNA and protein components. Much of our understanding of this pathway has come from studies performed with yeast model systems. These studies have identified critical checkpoints in the maturation of the large ribosomal subunit (LSU/60S), one of which is the proper formation and incorporation of the 5S ribonucleoprotein complex (5S RNP). Research on the 5S RNP has identified a complex containing the four proteins L5, L11, Rpf2, and Rrs1 as well as 5S rRNA. Our laboratory has studied the 5S RNP in Trypanosoma brucei, a eukaryotic parasite, and identified the proteins P34 and P37 as essential, parasite-specific members of this complex. We have additionally identified homologues of L5, Rpf2, Rrs1, and 5S rRNA in T. brucei and characterized their roles in this essential process. In this study, we examined the T. brucei homologue of ribosomal protein L11 as a member of the 5S RNP. We showed that TbL11 is essential and that it is important for proper ribosome subunit formation and 60S rRNA processing. Additionally, we identified TbL11 interactions with TbL5 and TbRpf2, as well as novel interactions with the kinetoplast-specific proteins P34 and P37. These findings expand our understanding of a crucial process outside the context of model yeast organisms and highlight differences in an otherwise highly conserved process that could be used to develop future treatments against T. brucei. IMPORTANCE The human-pathogenic, eukaryotic parasite Trypanosoma brucei causes human and animal African trypanosomiases. Treatments for T. brucei suffer from numerous hurdles, including adverse side effects and developing resistance. Ribosome biogenesis is one critical process for T. brucei survival that could be targeted for new drug development. A critical checkpoint in ribosome biogenesis is formation of the 5S RNP, which we have shown involves the trypanosome-specific proteins P34 and P37 as well as homologues of Rpf2, Rrs1, and L5. We have identified parasite-specific characteristics of these proteins and involvement in key parts of ribosome biogenesis, making them candidates for future drug development. In this work, we characterized the T. brucei homologue of ribosomal protein L11. We show that it is essential for parasite survival and is involved in ribosome biogenesis and rRNA processing. Furthermore, we identified novel interactions with P34 and P37, characteristics that make this protein a potential target for novel chemotherapeutics.

Typical structure of rRNA coding genes in diplonemids points to two independent origins of the bizarre rDNA structures of euglenozoans

“…One possible explanation is the ribosomal protein repertoire unique to this group. It has been shown that post-transcriptional removal of additional ITSs in T. brucei is guided by ribosomal proteins [ 45 ]. In general, kinetoplastid ribosomal proteins exhibit a number of unusual features interacting with unusual rRNA [ 22 , 46 , 47 ].…”

An Alba-domain protein required for proteome remodelling during trypanosome differentiation and host transition

“…Thus, Alba3 might play a role in polysome formation during the stumpy to procyclic transition. Alternatively, the effect might be indirect since the Alba3KO produces less TbL11, an essential factor in ribosome maturation [58], than the parental cells. In either case, however, it would imply that only a subset of translating ribosomes are affected, since the majority of proteins are present at similar levels in both cell lines.…”

Interactions of the Trypanosoma brucei brucei zinc-finger-domain protein ZC3H28

“…2B ), with a possible bias towards the small subunit. Fourteen of the 27 small subunit proteins were found, together with 14 of the 50 large subunit proteins, including the four acidic subunits and the Kinetoplastid-specific protein NRBD2 (Jaremko et al ., 2019 ). There was no obvious link between the detection of these proteins in the pull-down, and their protein sizes or their locations on the ribosome (Jenner et al ., 2012 ).…”