The UGG Isoacceptor of tRNAPro Is Naturally Prone to Frameshifts

摘要: Native tRNAs often contain post-transcriptional modifications to the wobble position expand capacity of reading genetic code. Some these modifications, due ability confer imperfect codon-anticodon pairing at position, can induce a high propensity for tRNA shift into alternative frames. An example is native UGG isoacceptor E. coli tRNAPro whose nucleotide U34 post-transcriptionally modified cmo5U34 read all four proline codons (5ʹ-CCA, 5ʹ-CCC, 5ʹ-CCG, and 5ʹ-CCU). Because anticodon CCC codon particularly weak relative CCA CCG codons, this readily both +1 +2-frame on slippery mRNA sequence CCC-CG. We show that more dominant, driven by higher stability position. Kinetic analysis suggests types shifts occur during stalling in post-translocation complex or translocation from A P-site. Importantly, while +1-frame post active peptidyl transfer, poor donor. Together with our recent work, we draw mechanistic distinction between +2-frameshifts, showing +1-shifts are suppressed additional m1G37 loop, +2-shifts ribosome, supporting role ribosome overall quality control reading-frame maintenance.