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A genetic study of primary and secondary reversions of some tryptophanA auxotrophs of Salmonella typhimurium

Published online by Cambridge University Press:  14 April 2009

S. Riyasaty  and
G. W. P. Dawson
S. Riyasaty
Affiliation:
Department of Genetics, Trinity College, Dublin
G. W. P. Dawson
Affiliation:
Department of Genetics, Trinity College, Dublin
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1. The linkage order of four tryA mutants of S. typhimurium, and cysB-12, is:

Attempts to plot the position of tryA-50 were unsuccessful.

2. Some of the reversions of tryA-8, tryA-47, tryA-56 and tryA-50 were analysed genetically; tryA-52 does not revert. All four auxotrophs gave reversions that were phenotypically and genetically indistinguishable from that expected by back-mutation of the original mutant site.

3. Both tryA-8 and tryA-50 produced reversions that grew as wild-type but were due to unlinked suppressor mutations. Some of these were super-suppressors in that they suppressed both tryA-8 and tryB-4; others suppressed many site mutants in the tryA gene but did not suppress tryB-4.

4. All the slow-growing reversions of tryA-8, tryA-50 and tryA-56, and a minority of the semi-fast reversions of tryA-8, were due to unlinked suppressors.

5. All the slow-growing reversions of tryA-47, the semi-fast reversions of tryA-56 and the majority of the semi-fast reversions of tryA-8 were due to genetic changes that were inseparable, in very extensive experiments, from their original mutant site.

6. Slow-growing reversions of tryA-47 produced faster growing mutants. Some of these were due to mutation in unlinked modifying genes and in others the genetic change was within the tryA gene. Nine of the latter had the genetic change just to the left of the 47S site; in one the change was inseparable from the 47S site. None had this further change to the right of the 47S site. These further changes, in the absence of the 47S site, gave prototrophic phenotypes; they are inter-site suppressors.

Type
Research Article
Information
Genetics Research , Volume 9 , Issue 3 , June 1967 , pp. 269 - 282
Copyright
Copyright © Cambridge University Press 1967

References

REFERENCES

Blume, A. J. & Balbinder, E. (1966). The tryptophan operon of Salmonella typhimurium. Fine structure analysis by deletion mapping and abortive transduction. Genetics, 53, 577–592.CrossRefGoogle ScholarPubMed
Brenner, S., Stretton, A. O. W. & Kaplan, S. (1965). Genetic code: the ‘nonsense’ triplets for chain termination and their suppression. Nature, Lond. 206, 994–998.CrossRefGoogle ScholarPubMed
Dawson, G. W. P. (1963). The interpretation of data from transduction experiments. Genet. Res. 4, 416–426.CrossRefGoogle Scholar
Demerec, M. (1963). Selfer mutants in Salmonella typhimurium. Genetics, 48, 1519–1531.CrossRefGoogle ScholarPubMed
Doy, C. H. (1966). Anthranilate synthetase and the allosteric protein model. Biochim. biophys. Acta, 118, 173–188.CrossRefGoogle ScholarPubMed
Garen, A., Garen, S. & Wilhelm, R. C. (1965). Suppressor genes for nonsense mutations. I, The Su-1, Su-2 and Su-3 genes of Escherichia coli. J. molec. Biol. 14, 167–178.CrossRefGoogle ScholarPubMed
Garen, A. & Siddiqi, O. (1962). Suppression of mutations in the alkaline phosphatase structural cistron of E. coli. Proc. natn. Acad. Sci. U.S.A. 48, 1121–1127.CrossRefGoogle ScholarPubMed
Margolin, P. (1963). Genetic fine structure of the leucine operon in Salmonella. Genetics, 48, 441–457.CrossRefGoogle ScholarPubMed
Smith-Keary, P. F. (1960). A suppressor of leucineless in Salmonella typhimurium. Heredity, Lond. 14, 61–71.CrossRefGoogle Scholar
Weigert, M. G. & Garen, A. (1965). Base composition of nonsense codons in E. coli. Evidence from amino-acid substitutions at a tryptophan site in alkaline phosphatase. Nature, Lond. 206, 992–994.CrossRefGoogle Scholar
Yanofsky, C., Helinski, D. R. & Maling, B. D. (1961). The effects of mutation on the composition and properties of the A protein of Escherichia coli tryptophan synthetase. Cold Spring Harb. Symp. quant. Biol. 26, 11–24.CrossRefGoogle Scholar
Zinder, N. D. (1955). Bacterial transduction. J. cell. comp. Physiol. 45, Suppl. 2, 23–49.CrossRefGoogle ScholarPubMed
Zinder, N. D. (1958). Lysogenization and superinfection immunity in Salmonella. Virology, 5, 291–326.CrossRefGoogle ScholarPubMed