Molecular and Functional Characterization of a Trypanosoma cruzi Nuclear Adenylate Kinase Isoform

Abstract

Trypanosoma cruzi, the etiological agent of Chagas' disease, is an early divergent eukaryote in which control of gene expression relies mainly in post-transcriptional mechanisms. Transcription levels are globally up and down regulated during the transition between proliferating and non-proliferating life-cycle stages. In this work we characterized a nuclear adenylate kinase isoform (TcADKn) that is involved in ribosome biogenesis. Nuclear adenylate kinases have been recently described in a few organisms, being all related to RNA metabolism. Depending on active transcription and translation, TcADKn localizes in the nucleolus or the cytoplasm. A non-canonical nuclear localization signal was mapped towards the N-terminal of the protein, being the phosphate-binding loop essential for its localization. In addition, TcADKn nuclear exportation depends on the nuclear exportation adapter CRM1. TcADKn nuclear shuttling is governed by nutrient availability, oxidative stress and by the equivalent in T. cruzi of the mammalian TOR (Target of Rapamycin) pathway. One of the biological functions of TcADKn is ribosomal 18S RNA processing by direct interaction with ribosomal protein TcRps14. Finally, TcADKn expression is regulated by its 3′ UTR mRNA. Depending on extracellular conditions, cells modulate protein translation rates regulating ribosome biogenesis and nuclear adenylate kinases are probably key components in these processes.

Inactive trans-Sialidase Expression in iTS-null Trypanosoma cruzi Generates Virulent Trypomastigotes

“…Regions of interest were amplified by PCR and synthetic DNA encoding the 3XFLAG epitope was inserted and assembled in pGEMT-Easy (see scheme in Figure 1A ). The full constructs were cloned into the EcoR V- Sal I sites of the T. cruzi expression vector pTrex-Omni , kindly provided by Dr. Claudio Pereira (Cámara et al, 2013 ). The final constructs were fully sequenced.…”

Nuclear Compartmentalization Contributes to Stage-Specific Gene Expression Control in Trypanosoma cruzi

“…The role of the nuclear compartment in the control of the cytoplasmic steady-state transcript levels has been recognized as crucial in eukaryotic gene expression regulation (Kohler and Hurt, 2007 ; Palazzo and Akef, 2012 ) and is also being studied in trypanosomatids (Nazer et al, 2011 , 2012 ; Fadda et al, 2014 ; Antwi et al, 2016 ; De Gaudenzi et al, 2016 ; Kramer et al, 2016 ), for a very recent review see (Clayton, 2016 ). Although specific molecular actors involved in the nucleus-cytoplasmic transport in T. cruzi are being unraveled (Cassola and Frasch, 2009 ; Serpeloni et al, 2011a , b ; Camara Mde et al, 2013 ; Inoue et al, 2014 ), no global analysis of the impact of nuclear compartmentation has been performed yet.…”

Mitochondrial and Nucleolar Localization of Cysteine Desulfurase Nfs and the Scaffold Protein Isu in Trypanosoma brucei

“…1). Even though a nuclear targeting sequence in trypanosomes was described only in a few cases (44)(45)(46)(47)(48), and no consensus sequence has been defined so far, the general rules postulating a high content of positively charged amino acids such as arginine seem to be universal. Thus, we hypothesize that the sequence RRRPR may function as a nuclear targeting signal in T. brucei as well.…”