TY  - JOUR
A1  - Fritz, Melanie
A1  - Vanselow, Jens
A1  - Sauer, Nadja
A1  - Lamer, Stephanie
A1  - Goos, Carina
A1  - Siegel, T. Nicolai
A1  - Subota, Ines
A1  - Schlosser, Andreas
A1  - Carrington, Mark
A1  - Kramer, Susanne
T1  - Novel insights into RNP granules by employing the trypanosome's microtubule skeleton as a molecular sieve
JF  - Nucleic Acids Research
N2  - RNP granules are ribonucleoprotein assemblies that regulate the post-transcriptional fate of mRNAs in all eukaryotes. Their exact function remains poorly understood, one reason for this is that RNP granule purification has not yet been achieved. We have exploited a unique feature of trypanosomes to prepare a cellular fraction highly enriched in starvation stress granules. First, granules remain trapped within the cage-like, subpellicular microtubule array of the trypanosome cytoskeleton while soluble proteins are washed away. Second, the microtubules are depolymerized and the granules are released.

RNA sequencing combined with single molecule mRNA FISH identified the short and highly abundant mRNAs encoding ribosomal mRNAs as being excluded from granules. By mass spectrometry we have identified 463 stress granule candidate proteins. For 17/49 proteins tested by eYFP tagging we have confirmed the localization to granules, including one phosphatase, one methyltransferase and two proteins with a function in trypanosome life-cycle regulation.

The novel method presented here enables the unbiased identification of novel RNP granule components, paving the way towards an understanding of RNP granule function.
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126180
ER  - 
TY  - JOUR
A1  - Goos, Carina
A1  - Dejung, Mario
A1  - Wehman, Ann M.
A1  - M-Natus, Elisabeth
A1  - Schmidt, Johannes
A1  - Sunter, Jack
A1  - Engstler, Markus
A1  - Butter, Falk
A1  - Kramer, Susanne
T1  - Trypanosomes can initiate nuclear export co-transcriptionally
JF  - Nucleic Acids Research
N2  - The nuclear envelope serves as important messenger RNA (mRNA) surveillance system. In yeast and human, several control systems act in parallel to prevent nuclear export of unprocessed mRNAs. Trypanosomes lack homologues to most of the involved proteins and their nuclear mRNA metabolism is non-conventional exemplified by polycistronic transcription and mRNA processing by trans-splicing. We here visualized nuclear export in trypanosomes by intra- and intermolecular multi-colour single molecule FISH. We found that, in striking contrast to other eukaryotes, the initiation of nuclear export requires neither the completion of transcription nor splicing. Nevertheless, we show that unspliced mRNAs are mostly prevented from reaching the nucleus-distant cytoplasm and instead accumulate at the nuclear periphery in cytoplasmic nuclear periphery granules (NPGs). Further characterization of NPGs by electron microscopy and proteomics revealed that the granules are located at the cytoplasmic site of the nuclear pores and contain most cytoplasmic RNA-binding proteins but none of the major translation initiation factors, consistent with a function in preventing faulty mRNAs from reaching translation. Our data indicate that trypanosomes regulate the completion of nuclear export, rather than the initiation. Nuclear export control remains poorly understood, in any organism, and the described way of control may not be restricted to trypanosomes.
KW  - molecular biology
KW  - nuclear export
KW  - trypanosomes
KW  - mRNA
KW  - nuclear envelope
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177709
VL  - 47
IS  - 1
ER  -