Mapping mRNP-NUP interactions during nuclear export with a unique mRNA-trap

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Eukaryotic mRNAs are transcribed in the nucleus and need to pass through the nuclear pores to reach the cytoplasm for translation. This passage is essential for mRNA function and failures are linked to a range of human diseases. The study of nuclear mRNA export is challenging, because it is very fast and interactions between mRNAs and nuclear pore proteins are transient. We recently found that trypanosomes lack the mRNA export checkpoint that usually prevents immature mRNAs from starting nuclear export. As a consequence, mRNAs with their attached proteins (mRNPs, messenger ribonucleoprotein particles) can be trapped while being exported, simply by blocking transcription or splicing. Here, we plan to employ this unique feature of trypanosomes as an mRNA trap to study interactions between mRNPs and nucleoporins. We will use a combination of newly developed proximity labeling techniques for proteins and RNA, complemented by classical biochemical purification approaches. Our combined data will create a map of interactions between the nuclear pore proteins and the mRNPs in transit with high spatial resolution. Despite the evolutionary distance, the basic structure of the nuclear pore is conserved in trypanosomes and it is likely that findings are transferrable to opisthokonts, where an ‘mRNA trap’ is not possible. Conversely, our approach will elucidate differences in mRNA export and export control between trypanosomatids and mammalian systems: The combined outcome from these studies will identify mechanisms that are unique to the parasite, advancing our knowledge on how the complex pathway of mRNA export has evolved. Moreover, those that represent vulnerable processes can be leveraged for drug development against the neglected tropical diseases African Sleeping Sickness, Chagas disease and Leishmaniasis.