Dominika Foretek

Coordination of tRNA transcription and processing

Dominika Foretek, IBB PAS
Supervisor: prof. Magdalena Rakowska-Boguta (IBB PAS)

Primary tRNA transcripts (pre-tRNAs) undergo several steps leading to its maturation, starting from removal of 5’ leader and 3’ trailer sequence through specific modifications and splicing of intron. One of enzymes involved in 3’end maturation of some tRNAs is 3'-5' exoribonuclease Rex1. Deletion of gene encoding this enzyme led to occurrence of longer, undefined pre-tRNA form. Appearance of longer pre-tRNAs in rex1Δ strain indicated defects in 3’ end processing and brought our focus to analyzing trailer sequences for some pre-tRNAs. Interestingly, the same longer form was observed in wild type stain grown undrer stress circumstances. Obtained results from Northern blots and sequencing suggests existence of additional regulation of tRNA maturation by growth conditions like: temperature, carbon source or amino acid availability. As in wild type strain La is competing with Rex1 for trailer binding and assists in endonucleolitic cleavage, we suggest that accumulation of longer pre-tRNA form in stress conditions in rex1ΔΔ strain is La-dependent. Finally, we showed differences in tRNA precursors for different intron containing tRNAs, what imply that this regulation would also be tRNA-type-specific.

Mrs. Chairwoman - prof. Elżbieta Malinowska

Discussion