Translational roles of the C75 2′OH in an in vitro tRNA transcript at the ribosomal A, P and E sites
Abstract Aminoacyl-tRNAs containing a deoxy substitution in the penultimate nucleotide (C75 2′OH → 2′H) have been widely used in translation for incorporation of unnatural amino acids (AAs). However, this supposedly innocuous modification surprisingly increased peptidyl-tRNAAla ugc drop off in bioch...
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| Autores principales: | , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Nature Portfolio
2017
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/4dc37467c9fb4614b130d381bb418576 |
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| Sumario: | Abstract Aminoacyl-tRNAs containing a deoxy substitution in the penultimate nucleotide (C75 2′OH → 2′H) have been widely used in translation for incorporation of unnatural amino acids (AAs). However, this supposedly innocuous modification surprisingly increased peptidyl-tRNAAla ugc drop off in biochemical assays of successive incorporations. Here we predict the function of this tRNA 2′OH in the ribosomal A, P and E sites using recent co-crystal structures of ribosomes and tRNA substrates and test these structure-function models by systematic kinetics analyses. Unexpectedly, the C75 2′H did not affect A- to P-site translocation nor peptidyl donor activity of tRNAAla ugc. Rather, the peptidyl acceptor activity of the A-site Ala-tRNAAla ugc and the translocation of the P-site deacylated tRNAAla ugc to the E site were impeded. Delivery by EF-Tu was not significantly affected. This broadens our view of the roles of 2′OH groups in tRNAs in translation. |
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