Dataset Information

Orthogonality of Pyrrolysine tRNA in the Xenopus oocyte.

ABSTRACT: Chemical aminoacylation of orthogonal tRNA allows for the genetic encoding of a wide range of synthetic amino acids without the need to evolve specific aminoacyl-tRNA synthetases. This method, when paired with protein expression in the Xenopus laevis oocyte expression system, can extract atomic scale functional data from a protein structure to advance the study of membrane proteins. The utility of the method depends on the orthogonality of the tRNA species used to deliver the amino acid. Here, we report that the pyrrolysyl tRNA (pylT) from Methanosarcina barkeri fusaro is orthogonal and highly competent for genetic code expansion experiments in the Xenopus oocyte. The data show that pylT is amendable to chemical acylation in vitro; it is then used to rescue a cytoplasmic site within a voltage-gated sodium channel. Further, the high fidelity of the pylT is demonstrated via encoding of lysine within the selectivity filter of the sodium channel, where sodium ion recognition by the distal amine of this side-chain is essential. Thus, pylT is an appropriate tRNA species for delivery of amino acids via nonsense suppression in the Xenopus oocyte. It may prove useful in experimental contexts wherein reacylation of suppressor tRNAs have been observed.

SUBMITTER: Infield DT

PROVIDER: S-EPMC5980078 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Orthogonality of Pyrrolysine tRNA in the Xenopus oocyte.

Infield Daniel T DT Lueck John D JD Galpin Jason D JD Galles Grace D GD Ahern Christopher A CA

Scientific reports 20180326 1

Chemical aminoacylation of orthogonal tRNA allows for the genetic encoding of a wide range of synthetic amino acids without the need to evolve specific aminoacyl-tRNA synthetases. This method, when paired with protein expression in the Xenopus laevis oocyte expression system, can extract atomic scale functional data from a protein structure to advance the study of membrane proteins. The utility of the method depends on the orthogonality of the tRNA species used to deliver the amino acid. Here, w ...[more]

PMID: 29581437

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Project description:To investigate the effects of adenosine on endogenous Xenopus oocyte receptors, we analysed defolliculated oocytes injected with mRNAs for the G protein-activated inwardly rectifying K(+) (GIRK) channels. In oocytes injected with mRNAs for either GIRK1/GIRK2 or GIRK1/GIRK4 subunits, application of adenosine or ATP reversibly induced inward K(+) currents, although ATP was less potent than adenosine. The responses were attenuated by caffeine, a non-selective adenosine receptor antagonist. Furthermore, in uninjected oocytes from the same donor, adenosine produced no significant current. The endogenous receptor was activated by two selective A(1) adenosine receptor agonists, N(6)-cyclopentyladenosine (CPA) and N(6)-cyclohexyladenosine (CHA), and antagonized by a selective A(1) adenosine receptor antagonist, 1,3-dipropyl-8-cyclopenylxanthine (DPCPX) at moderate nanomolar concentrations, but insensitive to micromolar concentrations of selective A(2A) and A(3) adenosine receptor agonists, 2-[p-(2-carbonyl-ethyl)-phenylethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680) and N(6)-(3-iodobenzyl)-5'-(N-methylcarbamoyl)adenosine (IB-MECA), respectively. However, the pharmacological characteristics of the receptor were different from those of the cloned Xenopus A(1) adenosine receptor and previously proposed adenosine receptors. The adenosine-induced GIRK currents were abolished by injection of pertussis toxin and CPA inhibited forskolin-stimulated cyclic AMP accumulation. We conclude that an adenosine receptor on the Xenopus oocyte membrane can activate GIRK channels and inhibit adenylyl cyclase via G(i/o) proteins. Moreover, our results suggest the existence of an endogenous adenosine receptor with the unique pharmacological characteristics. As the receptor was activated by nanomolar concentrations of adenosine, which is a normal constituent of extracellular fluid, the receptor may be involved in some effects through the G(i/o) protein signalling pathways in ovarian physiology.

Dataset Information

Orthogonality of Pyrrolysine tRNA in the Xenopus oocyte.

Publications

Orthogonality of Pyrrolysine tRNA in the Xenopus oocyte.

Similar Datasets

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