A
            <i>cis/trans</i>
            Test of the Effect of the First Enzyme for Histidine Biosynthesis on Regulation of the Histidine Operon

Kovach, John S.; Ballesteros, Antonio; Meyers, Marilyn; Soria, Marco R.; Goldberger, Robert F.

doi:10.1128/jb.114.1.351-356.1973

Cited by 17 publications

(14 citation statements)

References 17 publications

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“…2), the doubling time of 10 h obtained with 15 mM AMT is indicative of a drastic limitation in the availability of histidine. The same result, absence of derepressibility, was obtained by Kovach et al (18) in a merodiploid strain with chromosomal hisG deletion and episomal hisG feedback resistance, when also inhibited with 15 mM AMT, a concentration that severely affected growth rate. Patthy and Denes (33) have reported a feedback-insensitive mutant of E. coli K-12 able to derepress only when reaching a high histidine deprivation.…”

Section: Discussionsupporting

confidence: 81%

“…The study of the kinetic pattern of repression in various histidine auxotrophs in the presence of TA (19) and the finding that the histidine analogue TRA cannot cause repression of feedback-resistant mutants (21) led Kovach and colleagues (18) to conclude that the feedbacksensitive site of the first enzyme plays a role in regulation of the histidine operon. Later, they presented evidence indicating that the first enzyme must interact with his-tRNA to fulfill its regulatory properties (20).…”

Section: Discussionmentioning

confidence: 99%

“…Derepression of the hypersensitive bradytroph was effected with 40 mM AMT plus 15 MM histidinol. The design of the kinetic experiments was similar to that of Kovach et al (18,19). An MSE sonic oscillator was used to disrupt the cells.…”

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confidence: 99%

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Derepression and repression of the histidine operon: role of the feedback site of the first enzyme

Fernández¹,

Martín-del-Río²,

Tebar³

et al. 1975

J Bacteriol

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Thiazolealanine, a false feedback inhibitor, causes transient repression of the his operon previously derepressed by a severe histidine limitation in strains with a wild-type or feedback-hypersensitive first enzyme but not in feedback-resistant mutants. Since experiments reported here clearly demonstrate that thiazolealanine is not transferred to tRNAH"S, it is proposed that this "transient repression"is effected through the interaction of thiazolealanine with the feedback site of the enzyme. Experiments in the presence of rifampin indicate that this thiazolealanine-mediated effect is exerted at the level of translation. We conclude that histidine (free), in addition to forming co-repressor, also represses the operon at the level of translation through feedback interaction with the first enzyme of the pathway (adenosine 5'-triphosphate phosphoribosyltransferase). Rates of derepression in feedback-resistant strains are roughly half of those observed in controls, suggesting a positive role played by a first enzyme with a normal but unoccupied feedback site. Some feedback-resistant mutants, in contrast to the wild type, were unable to exhibit derepression under histidine limitation caused by aminotriazole.Extensive studies on the regulation of biosynthetic operons in microorganisms have shown that there are two different mechanisms by which end product biosynthesis is regulated. One mechanism, feedback inhibition (fine control), involves inhibition of the first enzyme of the pathway by the end product (43, 48) and determines the internal pool of this metabolite in the cell. The other mechanism, repression and derepression (coarse control), involves changes in the intracellular concentrations of the biosynthetic enzymes (16,44).The results of several studies suggest that feedback-sensitive first enzyme of a biosynthetic operon is involved in repression (5,6,13,20,21,24,26,36,40). In Salmonella typhimurium, the involvement of the first enzyme for histidine biosynthesis (G enzyme) [N-1-(5'-phosphoribosyl) adenosine triphosphate: pyrophosphate phosphoribosyltransferase, EC 2.4.2.171 in the regulation of the operon is well documented (20,21,36). In the present work, results of experiments designed to study derepression and repression of the histidine operon lead us to postulate that direct participation of the first enzyme in regulation at the level of translation involves the state of the feedback site of the enzyme. MATERIALS AND METHODS Bacterial strains. The organisms employed in this study, obtained from the collection of P. E. Hartman (12), were the LT2 (wild type) strain of S. typhimurium and several mutants derived from it (Table 1).Growth conditions and experimental design. Cells were routinely grown in minimal medium (45) with glucose at 0.4%. The cultures were aerated in a rotary shaker at 37 C. The histidine auxotrophs were grown in the presence of a sufficient amount of L-histidine to support growth to an absorbance at 650 nm of approximately 0.4; after depletion of histidine, growth was controlled with L-hi...

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Derepression and repression of the histidine operon: role of the feedback site of the first enzyme

Fernández¹,

Martín-del-Río²,

Tebar³

et al. 1975

J Bacteriol

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“…In all previously isolated feedback-resistant mutants, the K, of the phosphoribosyltransferase for histidine was raised by approximately one to two orders of magnitude (18,27). Our selection, which was previously reported (11), demanded a much greater alteration in K,. We report here results of biochemical and genetic tests that show that these mutants display a trans-recessive regulatory defect causing constitutive expression of the histidine operon.…”

mentioning

confidence: 94%

“…This evidence may be summarized as follows. (i) Some mutations that cause alteration of the allosteric properties of the enzyme also result in an altered pattern of repression by histidine and in an inability of the histidine analogue, 1,2,4-triazolalanine, to repress the histidine operon (11,12,14). (ii) Phosphoribosyltransferase interacts specifically, and with high affinity, with aminoacylated histidyl-tRNA (3, 13, 33).…”

mentioning

confidence: 99%

trans-Recessive mutation in the first structural gene of the histidine operon that results in constitutive expression of the operon

Meyers¹,

Levinthal²,

Goldberger³

1975

J Bacteriol

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The first enzyme for histidine biosynthesis, encoded in the hisG gene, is involved in regulation of expression of the histidine operon in Salmonella typhimurium. The studies reported here concern the question of how expression of the histidine operon is affected by a mutation in the hisG gene that alters the allosteric site of the first enzyme for histidine biosynthesis, rendering the enzyme completely resistant to inhibition by histidine. The intracellular concentrations of the enzymes encoded in the histidine operon in a strain carrying such a mutation on an episome and missing the chromosomal hisG gene are three- to fourfold higher than in a strain carrying a wild-type hisG gene on the episome. The histidine operon on such a strain fails to derepress in response to histidine limitation and fails to repress in response to excess histidine. Furthermore, utilizing other merodiploid strains, we demonstrate that the wild-type hisG gene is trans dominant to the mutant allele with respect to this regulatory phenomenon. Examination of the regulation of the histidine operon in strains carrying the feedback-resistant mutation in an episome and hisT and hisW mutations in the chromosome showed that the hisG regulatory mutation is epistatic to the hisT and hisW mutations. These data provide additional evidence that the first enzyme for histidine biosynthesis is involved in autogenous regulation of expression of the histidine operon.

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Regulation of Enzyme Synthesis in the Bacteria: A Comparative and Evolutionary Study

Clarke

1979

Biological Regulation and Development

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A cis/trans Test of the Effect of the First Enzyme for Histidine Biosynthesis on Regulation of the Histidine Operon

Cited by 17 publications

References 17 publications

Derepression and repression of the histidine operon: role of the feedback site of the first enzyme

Derepression and repression of the histidine operon: role of the feedback site of the first enzyme

trans-Recessive mutation in the first structural gene of the histidine operon that results in constitutive expression of the operon

Regulation of Enzyme Synthesis in the Bacteria: A Comparative and Evolutionary Study

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