RNA localization and targeting of proteins to cyanobacterial membranes

• Applicant: Professorin Dr. Annegret Wilde
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms ; Plant Physiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553555281

In eukaryotic cells, DNA is transcribed into RNA in the nucleus, and proteins are translated in the cytosol using these transcripts. In contrast, prokaryotic cells do not contain a nucleus; therefore, transcription and translation occur in the same compartment in bacteria and archaea. In my lectures teaching genetics to first-semester bachelor students, I used to show transcription and translation happening together, and almost at the same time in bacterial cells. However, new studies have suggested that this may not always be the case. Recent findings indicate that transcription and translation in bacteria may not always be synchronized. Instead, there can be times when these processes are separated by time or space, allowing for more precise control of gene expression. Such separation in a bacterial cell can be achieved by the accumulation of certain RNA species at different locations in the cell, for example, at membranes or in the form of condensates. In the current project proposal, we want to understand where RNA molecules are located in cyanobacterial cells using two independent experimental methods. First, RNA localization-sequencing, which combines cell fractionation and RNA-sequencing, and second, the visualization technique "RNA-fluorescence in situ hybridization" combined with high-resolution microscopy to identify whether RNAs are enriched at different locations in a cyanobacterial cell. Cyanobacteria are especially interesting for these analyses because they contain two different membrane systems, the thylakoid membrane, where all the photosynthetic proteins are located, and the plasma membrane that surrounds the cytosol. Our preliminary findings demonstrate that the transcriptome of cyanobacteria is indeed spatially organized. We found that several transcripts encoding proteins involved in photosynthesis accumulated at the thylakoid membrane in a translation-independent manner. RNA-binding proteins play key roles in this mechanism. In this proposal, we aim to determine the fate of RNAs in cyanobacterial cells by examining subcellular RNA organization and the roles of RNA-binding proteins and ribonucleases to gain a better understanding of the mechanisms underlying differential RNA enrichment patterns. We will mainly focus on the enrichment of RNAs at the two membrane systems to understand why membrane proteins are inserted into the correct membrane.

• DFG Programme: Research Grants