Interakce mezi antikodonovým ramenem tRNA a malými ribozomálními proteiny tvořícími dekódovací místo při pročtení stop kodonu

Čapková, Zuzana

Transfer RNAs (tRNAs) represent an indispensable part of protein synthesis by delivering amino acids into ribosomal A site during elongation. The rules that govern the correct match between the tRNA anticodon and the A-site mRNA codon are set by the genetic code. Specifically, the code defines that 61 sense codons are recognized by tRNAs and 3 stop codons marking translation termination are recognized by the release factor. In certain circumstances, a near-cognate (or a cognate) tRNA can be incorporated at the stop codon and translation elongation proceeds further. This process, called stop codon readthrough, may be beneficial as a therapy for inherited genetic diseases caused by premature termination codons (PTCs), and importantly, it is crucial for organisms with stop codon reassignment(s). Here I show that apart from the anticodon itself, the peculiar anticodon stem of two different near-cognate tRNAs, namely yeast S. cerevisiae tRNAGln CUG and Blastocrithidia nonstop tRNATrp CCA, is critical for their readthrough promoting potential. In particular, yeast tRNAGln CUG relies on the specific pyrimidine 28 : purine 42 base pair forming the 4th pair of its anticodon stem, whereas tRNATrp CCA of B. nonstop acquired a mutation that shortened its anticodon stem from the canonical 5 to the 4 base pairs,...

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