Mirjam Thielen (Rheinische Friedrich-Wilhelms-Universität Bonn)
Mirjam Thielen's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Bonn University in the year 2023 with the title:
Establishing cytosolic C-to-U RNA editing in Physcomitrium patens and investigating the influence of knocked out DYW-type pentatricopeptide repeat editing factors under various stress conditions
For the first time Thielen showed, that cytidine-to-uridine RNA-editing, which is naturally restricted to plant chloroplasts and mitochondria, is principally possible also in the cytosol using the moss Physcomitrium patens as a model system.
Plant-type cytidine-to-uridine RNA editing is performed by nuclear encoded RNA-binding pentatricopeptide repeat (PPR) proteins and affects transcripts in the mitochondria and chloroplasts but is suspiciously absent in the nucleo-cytosolic compartment. To investigate whether RNA editing factors could principally perform RNA editing in the cytosol, too, recombinant constructs of three characterized editing factors and their co-transcribed targets were transformed into Physcomitrium patens using an inducible expression setup. Cytosolic C-to-U RNA editing could be verified not only for the native targets artificially provided but also for up to hundreds of off-targets in the moss background transcriptome. The latter finding demonstrates restricted target recognition specificity and likely explains why plant RNA editing is restricted to the smaller transcriptomes of the endosymbiotic organelles in nature. However, the now available conservation profiling of off-targets will help to elucidate the details of PPR-RNA interactions towards possible future biotechnical approaches to engineer transcriptome targeting.
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Mirjam Thielen conducted this work at the Institute for Cellular and Molecular Botany in the research group Molekulare Evolution of Prof. Dr. Volker Knoop.
