Regulatory function of the tRNA 3'-end in E. coli

• Applicants: Dr. Andreas Czech; Professor Dr. Mario Mörl
• Subject Area: Biochemistry
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 277430113

Transfer RNAs (tRNAs) play a crucial role in protein synthesis. They are synthesized as precursor molecules and mature through a complex pathway, including post-transcriptional modification. Misfolded or hypomodified tRNA are selectively degraded. Exposure to stress alters the tRNA structure. In previous collaborative work we showed that in mammalian cells under stress conditions the ubiquitous CCA-end is shortened and consequently, the tRNA is reversibly inactivated and withdrawn from translation, but not degraded. In contrast, the addition of extra CCA triplets to the 3'-end acts as a degradation signal. Information on whether such alterations in tRNA are conserved among species and determine the tRNA availability for translation in prokaryotes is still unknown. Thus, in this collaborative project we aim to elucidate the impact of CCACCA addition on tRNA stability as well as to identify the RNases and accessory proteins that degrade tRNA in Escherichia coli. We will employ various in vitro assays, including RNase assays, pull down experiments on cell lysates and complement them with in vivo sequencing studies in KO-strains and upon exposure to stress. Thereby, the main intriguing question is to elucidate how the cell differentiates between tRNAs tagged for degradation and tRNA precursors as both share high structural and sequence similarity. Our studies will deliver important new insights into tRNA regulation under physiological and stress conditions.

• DFG Programme: Research Grants