A Proposal for a Uniform Nomenclature in Bacterial Genetics

121

A class of mutations that confer resistance to rifampin in Salmonella typhimurium and Escherichia coli also suppresses the thermosensitivity of chromosome initiation in dnaA mutants. Ribonucleic acid polymerase is resistant to rifampin in vitro in these suppressive mutants, and the suppressors of dnaA cannot be separated from the rpoB mutations by transduction. It is concluded, therefore, that certain rpoB mutations may suppress the DnaA phenotype.

“…The characteristics and source of the strains are listed in Table 1. Genetic nomenclature is in accord with the suggestions of Demerec et al (10), Sanderson (20), and Bachmann et al (1).…”

Section: Methodsmentioning

confidence: 84%

Suppression of the DnaA phenotype by mutations in the rpoB cistron of ribonucleic acid polymerase in Salmonella typhimurium and Escherichia coli

Izakowska¹,

Bagdasarian²

1977

121

“…(Genotypes are referred to throughout by the symnbols proposed by Bachmann et al [31 and Demerec et al [7].) Selection and testing of ethiomine-resistant mutants.…”

mentioning

confidence: 99%

Isolation of a metK mutant with a temperature-sensitive S-adenosylmethionine synthetase

Hafner¹,

Tabor²,

Tabor³

1977

An Escherichia coli metK mutant, designated metK110, was isolated among spontaneous ethionine-resistant organisms selected at 42 degrees C. The S-adenosylmethionine synthetase activity of this mutant was present at lower levels than in the corresponding wild-type strain and was more labile than the wild-type enzyme when heated or dialyzed. A mixture of mutant and wild-type enzyme preparations had an activity equal to the sum of the component activities. These facts strongly suggest that the mutated gene in this strain is the structural gene for this enzyme. Genetic mapping experiments placed the metK110 mutation near or at the site of other known metK mutants (i.e., 63 min), confirming its designation as a metK mutant. A revised gene order has been established for this region, i.e., metC glc speC metK speB serA.

“…recA-strains of Escherichia coli K-12 are deficient in genetic recombination and in repair of a variety of deoxyribonucleic acid (DNA) lesions including pyrimidine dimers produced by irradiation with ultraviolet (UV) light (for review, see Clark [7]). They also respond abnormally to UV irradiation in certain other respects that have been reviewed recently (17).…”

mentioning

confidence: 99%

“…BACTERIOL. (7) and Taylor and Trotter (22). lexA refers to a lex mutation at 80.9 min on the E. coli K-12 linkage map.…”

mentioning

confidence: 99%

Effect of tsl mutations in decreasing radiation sensitivity of a recA- strain of Escherichia coli K-12

Mount¹,

Walker²,

Kosel³

1975

It has been shown previously that the radiation sensitivity of lexA- strains of Escherichia coli K-12 can be suppressed by thermosensitive mutations (designated tsl) that are closely linked to the lexA locus and are thought to be intragenic suppressors of lexA mutations (Mount et al., 1973). When a recA mutation is crossed into a suppressed tsl- strain, the extreme radiation sensitivity usually conferred by a recA mutation is decreased, but there is no detectable change in genetic recombination deficiency. Increased resistance to UV in the tsl-reA-strains depends upon ability to synthesize active uvrA+ product.