PMID: 39221Jul 24, 1979

Suppressor mutations causing partial reversion in the amiA region of Pneumococcus

Molecular & General Genetics : MGG
Y George, L O Butler

Abstract

Mutants of an aminopterin-resistant strain of pneumococcus possessing four different suppressor genes have been isolated after mutagenesis with 5-BUdR. The suppressed strains exhibit a partial revertant phenotype since the parental aminopterin resistance remained unchanged but the associated sensitivity to an excess concentration of the branched chain amino acids L-isoleucine, L-valine and L-leucine was diminished almost to the level of the wild-type strain C13. The suppressor mutations had therefore dissociated the two properties associated with a mutation in the amiA cistron, namely aminopterin resistance and isoleucine sensitivity. The suppressor genes reduced the sensitivity to isoleucine of a number of amiA mutants, but had no effect on the level of resistance to a number of unrelated genes conferring resistance to other antibacterial substances. The suppressor mutations themselves did not confer resistance to aminopterin. Mapping of the suppressor mutations by recombination analysis and by clonal analysis showed them to be intragenic lying in the region near to the amiA-r19, amiA-r23, amiA-r17 loci.

Citations

Oct 1, 1967·Journal of Bacteriology·R Nagel de Zwaig, S E Luria
May 1, 1970·Journal of General Microbiology·L O Butler, M B Smiley
Apr 20, 1967·Biochemical and Biophysical Research Communications·E AzoulayF Pichinoty
Apr 22, 1960·Biochimica Et Biophysica Acta·S LACKS, R D HOTCHKISS

Related Concepts

Antibiotic Resistance, Microbial
Valine
Recombination, Genetic
Suppressor Mutation
Alloisoleucine
Clone
Transformation, Bacterial
Isoleucine Measurement
Mutant
Mutagenesis Procedure

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