Genetic characterization of the sufj frameshift suppressor in Salmonella typhimurium
Bossi, L.; Kohno, T.; Roth, J.R.
Genetics 103(1): 31-42
1983
ISSN/ISBN: 0016-6731 PMID: 6188650 Document Number: 218243
A new suppressor of + frameshift mutations was isolated in S. typhimurium. This suppressor, sufJ, maps at min 89 on the Salmonella genetic map between the argH and rpo(rif) loci, closely linked to the gene for the ochre suppressor tyrU(supM). The suppressor mutation is dominant to its wild-type allele, consistent with the suppressor phenotype being caused by an altered tRNA species. The sufJ map position coincides with that of a threonine tRNA(ACC/U) gene; the suppressor reads the related 4-base codons ACCU, ACCC, ACCA. The ability of sufJ to correct 1 particular mutation depends on the presence of a hisT mutation which causes a defect in tRNA modification. This requirement is allele specific, since other frameshift mutations can be corrected by sufJ, regardless of the state of the hisT locus. Strains carrying a sufJ and a hisT mutation are acutely sensitive to growth inhibition by uracil; the inhibition is reversed by arginine. This behavior is characteristic of strains with mutations affecting the arginine-uracil biosynthetic enzyme carbamyl phosphate synthetase. The combination of 2 mutations affecting tRNA structure may reduce expression of the structural gene for this enzyme (pyrA).