Investigation of cytoplasmic long noncoding RNA in Saccharomyces cerevisiae

by Theresa Binder
Doctoral thesis
Date of Examination:2024-12-10
Date of issue:2025-06-12
Advisor:Prof. Dr. Heike Krebber
Referee:Prof. Dr. Heike Krebber
Referee:Prof. Dr. Jörg Großhans
Referee:Prof. Dr. Stefanie Pöggeler
Referee:Prof. Dr. Kai Heimel
Referee:PD Dr. Wilfried Kramer
Referee:Dr. Achim Dickmanns
Persistent Address: http://dx.doi.org/10.53846/goediss-11242

 

 

Files in this item

Name:Thesis Theresa Binder.pdf
Size:7.72Mb
Format:PDF
Description:Dissertation

This file will be freely accessible after 2025-12-09.

Abstract

English

Research on lncRNAs has increased in the past, but little is known about their function. Recently, discoveries have given us insight into sense- and asRNA regulation in yeast. dsRNA is formed in the nucleus and shuttles into the cytoplasm to boost senseRNA gene expression. Still, these new findings do not focus on individual sense- and asRNA pairs, but show a general mechanism. The iron metabolism is well studied in yeast and consists of a complex mechanism to adapt to the nutritional availability of iron. The metalloreductase family which reduces iron consists of Fre1-Fre6 which are needed to adapt to a low iron environment. Thereby, the function of Fre5 is rather uncharacterized. This study proposes that Fre5 reduces iron at the mitochondria to ensure heme and iron sulfur cluster synthesis, which are crucial for the proper function of the cell and reveals the regulation of FRE5 by its respective asRNA SUT802. Both form a double strand in the nucleus which stabilizes FRE5. dsFRE5/SUT802 reaches the cytoplasm and is bound by the translational repressor Hek2, which is recruited by SUT802. As a result, FRE5 is translationally repressed under high iron conditions to counteract possible overproduction of Fe(II) at the mitochondria. Under low iron conditions, the Hek2 mediated inhibition is abrogated and the dsFRE5/SUT802 reaches the ribosome. This leads to translation of FRE5 and degradation of SUT802 via NMD. This asRNA mediated repression of senseRNA might not only be valid for Fre5 repression, but might also be mediated by the asRNA SUT322 to repress the low affinity iron importer FET4 under high iron conditions. Outside the iron metabolism, we show that Hek2 binds to a cytoplasmic lincRNA SUT098. SUT098 is cleaved by Rnt1 before export into the cytoplasm, where it is stabilized due to binding of Hek2. Together, these results reveal Hek2 binding to different classes of lncRNA and show a tight mechanism for posttranscriptional regulation of a senseRNA by its respective asRNA via Hek2.
Keywords: intergenic lncRNA; asRNA; FRE5; SUT802; SUT098