Abstract
SummaryNucleo‐cytoplasmic RNA export is an essential post‐transcriptional step to control gene expression in eukaryotic cells and is poorly understood in apicomplexan parasites. With the exception of UAP56, a component of TREX (Transcription Export) complex, other components of mRNA export machinery are not well conserved in divergent supergroups. Here, we use Toxoplasma gondii as a model system to functionally characterize TgUAP56 and its potential interaction factors. We demonstrate that TgUAP56 is crucial for mRNA export and that functional interference leads to significant accumulation of mRNA in the nucleus. It was necessary to employ bioinformatics and phylogenetic analysis to identify orthologs related to mRNA export, which show a remarkable low level of conservation in T. gondii. We adapted a conditional Cas9/CRISPR system to carry out a genetic screen to verify if these factors were involved in mRNA export in T. gondii. Only the disruption of TgRRM_1330 caused accumulation of mRNA in the nucleus as found with TgUAP56. This protein is potentially a divergent partner of TgUAP56, and provides insight into a divergent mRNA export pathway in apicomplexans.
Highlights
Nucleo-cytoplasmic RNA export is an essential posttranscriptional pathway to control gene expression in eukaryotic cells
We demonstrate that TgUAP56 is crucial for messenger RNAs (mRNAs) export and that functional interference leads to significant accumulation of mRNA in the nucleus
It was necessary to employ bioinformatics and phylogenetic analysis to identify orthologs related to mRNA export, which show a remarkable low level of conservation in T. gondii
Summary
Nucleo-cytoplasmic RNA export is an essential posttranscriptional pathway to control gene expression in eukaryotic cells. In general proteins of THO complex associate with mRNA and recruit processing and export factors resulting in the formation of the Transcription/Export (TREX) complex (Strasser et al, 2002). TREX complex interacts with the spliceosome and mature mRNAs are exported through the nuclear pore complex (NPC) by binding to the heterodimeric receptor Mex67:Mtr2/TAP:p15, in an Ran-independent manner (reviewed by (Katahira, 2015; Wickramasinghe and Laskey, 2015)). The mRNAs are released for translation into the cytoplasm by ATP-dependent helicase Dbp5/DDX19 (Kohler and Hurt, 2007; Nino et al, 2013)
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