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. 1977 Jun;86(2):261–274.

Amino Acid Replacements Resulting from Suppression and Missense Reversion of a Chain-Terminator Mutation in Neurospora

T W Seale 1, M Brett 1, A J Baron 1, J R S Fincham 1
PMCID: PMC1213676  PMID: 18380

Abstract

The Neurospora crassa super-suppressor mutation, ssu-1, suppresses the auxotrophic phenotype of the mutant am(17) by inserting tyrosine at residue 313 of NADP-specific glutamate dehydrogenase, a position occupied in the wild type by glutamate. Two classes of am(17) revertants due to further mutation within the am gene have, respectively, tyrosine and leucine at residue 313. These replacements are consistent with a chain-terminating codon in am(17) of either the amber (UAG) or the ochre type (UAA), but are inconsistent with UGA. The Leu313 and Tyr313 variants of the enzyme have effective activity but are grossly different from the wild type in Michaelis constants (especially for ammonium) and heat stabilities at two different pH values. They show smaller but significant differences in these respects from each other.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bruenn J., Jacobson K. B. New species of tyrosine tRNA in nonsense suppressor strain of yeast. Biochim Biophys Acta. 1972 Nov 16;287(1):68–76. doi: 10.1016/0005-2787(72)90330-9. [DOI] [PubMed] [Google Scholar]
  2. Capecchi M. R., Hughes S. H., Wahl G. M. Yeast super-suppressors are altered tRNAs capable of translating a nonsense codon in vitro. Cell. 1975 Nov;6(3):269–277. doi: 10.1016/0092-8674(75)90178-6. [DOI] [PubMed] [Google Scholar]
  3. Case M. E., Giles N. H. Evidence for nonsense mutations in the arom gene cluster of Neurospora crassa. Genetics. 1968 Sep;60(1):49–58. doi: 10.1093/genetics/60.1.49. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Chalmers J. H., Jr, Seale T. W. Supersuppressible mutants in Neurospora: mutants at the tryp-1 and tryp-2 loci affecting the structure of the multienzyme complex in the tryptophan pathway. Genetics. 1971 Mar;67(3):353–363. doi: 10.1093/genetics/67.3.353. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Gesteland R. F., Wolfner M., Grisafi P., Fink G., Botstein D., Roth J. R. Yeast suppressors of UAA and UAG nonsense codons work efficiently in vitro via tRNA. Cell. 1976 Mar;7(3):381–390. doi: 10.1016/0092-8674(76)90167-7. [DOI] [PubMed] [Google Scholar]
  6. Gilmore R. A., Stewart J. W., Sherman F. Amino acid replacements resulting from super-suppression of a nonsense mutant of yeast. Biochim Biophys Acta. 1968 Jun 18;161(1):270–272. doi: 10.1016/0005-2787(68)90322-5. [DOI] [PubMed] [Google Scholar]
  7. Stewart J. W., Sherman F., Jackson M., Thomas F. L., Shipman N. Demonstration of the UAA ochre codon in bakers yeast by amino-acid replacements in iso-1-cytochrome c. J Mol Biol. 1972 Jul 14;68(1):83–96. doi: 10.1016/0022-2836(72)90264-1. [DOI] [PubMed] [Google Scholar]
  8. Wootton J. C., Taylor J. G., Jackson A. A., Chambers G. K., Fincham J. R. The amino acid sequence of Neurospora NADP-specific glutamate dehydrogenase. The tryptic peptides. Biochem J. 1975 Sep;149(3):739–748. doi: 10.1042/bj1490739. [DOI] [PMC free article] [PubMed] [Google Scholar]

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