Frameshift suppression at tandem AGA and AGG codons by cloned tRNA genes: assigning a codon to argU tRNA and T4 tRNAArg (original) (raw)

Journal Article

R.A. Spanjaard ,

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K. Chen ,

1

Department of Microbiology, University of Texas

Austin, TX 78712-1095, USA

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J.R. Walker ,

1

Department of Microbiology, University of Texas

Austin, TX 78712-1095, USA

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J. van Duin

*To whom correspondence should be addressed

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+Present address: Division of Genetics, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA

Author Notes

Revision received:

06 August 1990

Published:

11 September 1990

Cite

R.A. Spanjaard, K. Chen, J.R. Walker, J. van Duin, Frameshift suppression at tandem AGA and AGG codons by cloned tRNA genes: assigning a codon to argU tRNA and T4 tRNAArg, Nucleic Acids Research, Volume 18, Issue 17, 11 September 1990, Pages 5031–5036, https://doi.org/10.1093/nar/18.17.5031
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Abstract

Arginine is coded for by CGN (N = G, A, U, C), AGA and AGG. In Escherichia coli there is little tRNA for AGA and AGG and the use of these codons is strongly avoided in virtually all genes. Recently, we demonstrated that the presence of tandem AGA or AGG codons in mRNA causes frameshifts with high frequency. Here, we show that phaseshifts can be suppressed when cells are transformed with the gene for tRNAT4Arg or _E. coli_tRNAargUArg⁠, demonstrating that such errors are the resulf of tRNA depletion. Bacteriophage T4 encoded tRNAArg (anticodon UCU) corrects shifts at AGA-AGA but not at AGG-AGG, suggesting that this tRNA can only read AGA. Similarly, comparison of the translational efficiencies in an argU (Ts) mutant and in its isogenic wild type parent indicates that argU tRNA (anticodon UCU) reads AGA but not AGG. An argU (Ts) mutant barely reads through AGA-AGA at 42°C but translation of AGG-AGG is hardly, if at all, affected. Overexpression of argU+ relaxes the codon specificity. The thermosensitive mutant in argU, previously called dnaY because it is defective in DNA replication, can be complemented for growth by the gene for tRNAT4Arg⁠. This implies that the sole function of the argU gene product is to sustain protein synthesis and that its role in replication is probably indirect.

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Author notes

+Present address: Division of Genetics, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA

© 1990 Oxford University Press

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