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Journals and Conferences
Preliminary genetic studies of pleiotropic chl-r mutants of Salmonella typhimurium LT2 were performed, which lead to the description of a new chl locus at 123 min on the chromosomal map. By analogy with Escherichia coli K12, it is called chl-B.
The ana mutation leads E. coli to need an exogenous electron acceptor for anaerobic growth. The affected gene maps near 26 min between chlC and tdk on the chromosome of the organism.
Several mutants unable to utilize trehalose were isolated from Escherichia coli. Their genetic analysis led to determine the following gene order on the chromosomal map: pur B-dad R-tre-hem A-trp. Furthermore, the tre gene belongs to the inversion of the trp chromosomal region between E. coli and S. typhimurium.
Five mutants of Escherichia coli impaired on nitrite reduction were studied. All have lost NADH-nitrite reductase activity but have retained the capacity to synthesize all or part of their cytochrome c552. Three genes, nir C, nir D, and nir E were mapped at 26, 72.5 and 49.5 min, respectively. Another gene, nir F was tentatively localized around 52 min.
Introduction of chlA, B or E mutant alleles into strains carrying fusions between the lac structural genes and the promoter of the nitrate reductase operon led to the partial or total constitutive expression of the fusion. Presence of chlD mutated alleles in the same strains did not result in constitutive expression of the fusion and allowed full induction… (More)
A nar-lac operon fusion was used to isolate a mutant in which the expression of the nar operon was no longer repressed by oxygen. The nar d mutation, located upstream of the nar structural genes, was found to be cis dominant; it led to independence from the Fnr protein which, in the wild-type strain, exerts a strict positive control on the nar operon. Both… (More)
Strains carrying operon fusions between the promotor of the chl I gene and the lac structural genes were constructed. From these strains in which the expression of the lac genes is under the control of both nitrate and oxygen, spontaneous regulatory mutants were selected: (i) mutants which synthesize β-galactosidase constitutively in anaerobiosis; (ii)… (More)