Mechanism Studies of Suppressor-Gene Action

Abstract

Mechanism studies of suppressor-gene action. J. Bacteriol. 90:687-695. 1965.-Mutations which change the primary structure of the A protein of the tryptophan synthetase of Escherichia coli can be reversed by allele-specific suppressor mutations. Normally, the suppressors of a particular A mutant lead to the appearance of small amounts of a wild-type-like A protein (su-A protein), in addition to the cross-reacting material antigenically similar to the normal A protein (CRM-A protein). In some cases, the particular ratio of su-A protein to CRM-A protein, indicative of a given suppressor gene, was increased when that suppressor gene was transduced into a different strain, such as a K-12 Hfr stock of E. coli. In these cases, there was a general correlation between an increased ratio and a marked instability of the suppressor gene. However, stable suppressed stocks were isolated in the Hfr strain, which also produced a high proportion of su-A protein. The ratios of su-A protein to CRM-A protein remained relatively constant under conditions of tryptophan repression in three different suppressor stocks, suggesting that the formation of each of the su-A proteins does not involve the interaction of a CRM-A protein with any other cellular constituent. It would appear, then, that the changes in the primary structure of the A protein which lead to the formation of the su-A proteins are determined before or during, but not after, the synthesis of the polypeptide chain. The specificity of amino acid activation was investigated in strains bearing one of the suppressor genes. These studies failed to reveal any significant alteration in the amino acyl ribonucleic acid (RNA) synthetases or the transfer RNA molecules for arginine, glycine, histidine, and tyrosine.

Organization of genes for transcription and translation in the rif region of the Escherichia coli chromosome

“…Comparison with the standard gel pattern in this system ( 4, tRNA4j"; spots 5 and 6, tRNA3T r; spot 7, tRNA2GIY; and spot 8, tRNA2GIU. RNA species known to be contained in t are: spot A, 5S RNA; spot B, tRNA2T' tRNA4Jhr and other tRNA's; spot D, tRN.…”

“…The presence of the glyT gene on Arifdl8 was the other also demonstrated by a genetic method. It is it pattern known that the glyT gene can be mutated to a ,hat of an missense suppressor glyT36(Su) (4,5,12). A vorkers in bacterial strain (N01818) (42) which carries the A2TYr (14).…”

Mechanisms and Delivery of tRNA Therapeutics

“…The two isolated trpA proteins differed by a single amino acid, and either had a Gly or an Arg residue at a particular site. Suppressors of trpA36 were mutant tRNA species that were able to insert Gly at Arg codons 197 or Gly at Cys codons in trpA78. 198 Further studies demonstrated that two trpA36 suppressors occurred in two different glycine tRNA genes.…”

T4 Bacteriophage Mutants Suppressible by a Missense Suppressor Which Inserts Glycine in Place of Arginine for the Codon AGA

“…The virus replicates in human cells and causes their destruction within a short period of time. In hamster cells, replication of viral deoxyribonucleic acid (DNA) is not demonstrable, as a rule, and thus no infectious progeny is produced (3,6,11). A small fraction of the infected hamster cells may become transformed (6, 9).…”