pretRNAknippen

PretRNAknippen, or pre-tRNA processing, is the set of enzymatic steps by which precursor tRNA transcripts are converted into mature tRNA molecules capable of guiding protein synthesis. In most organisms, tRNA genes are transcribed as longer precursors that carry extra sequences at the 5' and 3' ends and, in many cases, introns that interrupt the tRNA sequence. The processing pathway removes these extras, forms the correct cloverleaf structure, and prepares the molecule for aminoacylation.

5' end processing typically involves an RNase P–type endonuclease that cleaves off the 5' leader sequence. 3' end processing trims the trailer from the 3' end, often by a dedicated endonuclease or exonucleases, and is followed by addition of the CCA terminus by a CCA-adding enzyme when the genome does not encode CCA directly on the tRNA gene.

For tRNAs that harbor introns, the intron is removed by a tRNA splicing endonuclease; the resulting exons are joined by a tRNA ligase, producing a continuous mature tRNA.

Beyond trimming and splicing, pretRNAknippen includes base modification by modifying enzymes, which install modified nucleosides that stabilize the tRNA's structure and influence decoding fidelity. After processing, mature tRNAs are folded, charged with their corresponding amino acids, and trafficked to their functional locations, such as the cytoplasm or mitochondria.