Physiological and Kinetic Studies with Anthranilate Synthetase of
            <i>Bacillus alvei</i>

Catena, Anthony; DeMoss, R. D.

doi:10.1128/jb.101.2.476-482.1970

Cited by 15 publications

(7 citation statements)

References 25 publications

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“…2 and 4. Similar observations have been reported with the glutamine-reactive anthranilate synthase from Bacillus alvei (2); that is, the activity of this enzyme from B. alvei was not a linear function of protein concentration, and there was a rapid decrease in the activity of the enzyme during repression (2).…”

Section: Ex + Glutamine +_'ex Glutaminesupporting

confidence: 83%

Rapid Regulation of an Anthranilate Synthase Aggregate by Hysteresis

et al. 1973

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The anthranilate synthase aggregate from Bacillus subtilis is composed of two nonidentical subunits, denoted E and X, which are readily associated or dissociated. A complex of subunit E and X can utilize glutamine or ammonia as substrates in the formation of anthranilate. Partially purified subunit E is capable of using only ammonia as the amide donor in the anthranilate synthase reaction. The stability of the EX complex is strongly influenced by glutamine and by the concentrations of the subunits. Glutamine stabilizes the aggregate as a molecular species in which the velocity of the glutamine-reactive anthranilate synthase is a linear function of protein concentration. In the absence of glutamine the aggregate is readily dissociated following dilution of the extract; that is, velocity concaves upward as a function of increasing protein concentration. Reassociation of the EX complex is characterized by a velocity lag (or hysteretic response) before steady-state velocity for the glutamine-reactive anthranilate synthase is reached. We propose that association and dissociation of the anthranilate synthase aggregate may be physiologically significant and provide a control mechanism whereby repression or derepression causes disproportionate losses or gains in activity by virtue of protein-protein interactions between subunits E and X.

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Section: Ex + Glutamine +_'ex Glutaminesupporting

confidence: 83%

Rapid Regulation of an Anthranilate Synthase Aggregate by Hysteresis

et al. 1973

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“…The reaction mixture was incubated for 12 min at 30 C. The concentrations of chorismate and glutamine were 1 and 40 mm, respectively. Catena and DeMoss (16). However, in all other instances reported, tryptophan inhibits AS activity competitively with respect to chorismate (27,33,36,53,56) and noncompetitively with respect to glutamine in S. typhimurium -5.0 -4.0 -3.0 -2.0 and C. violaceum (27,53).…”

Section: Resultsmentioning

confidence: 86%

“…Studies carried out primarily with gramnegative bacteria have led to the formulation of various modes of regulation for the expression of the genes of the tryptophan biosynthetic enzymes. In most of the microorganisms examined thus far, the enzymes of tryptophan biosynthesis are repressible (9,18,34,45), and anthranilate synthetase (AS) is sensitive to feedback inhibition by tryptophan (7,16,22,44,53,56). In Escherichia coli, the enzymes were initially reported to be synthesized coordinately (34); however, Morse and Yanofsky (43) have demonstrated semicoordinate control of these enzymes.…”

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confidence: 99%

Regulation of the Tryptophan Synthetic Enzymes in Clostridium butyricum

Baskerville

Twarog

1972

J Bacteriol

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Experiments concerned with the regulation of the tryptophan synthetic enzymes in anaerobes were carried out with a strain of Clostridium butyricum. Enzyme activities for four of the five synthetic reactions were readily detected in wild-type cells grown in minimal medium. The enzymes mediating reactions 3, 4, and 5 were derepressed 4to 20-fold, and the data suggest that these enzymes are coordinately controlled in this anaerobe. The first enzyme of the pathway, anthranilate synthetase, could be derepressed approximately 90-fold under these conditions, suggesting that this enzyme is semicoordinately controlled. Mutants resistant to 5-methyl tryptophan were isolated, and two of these were selected for further analysis. Both mutants retained high constitutive levels of the tryptophan synthetic enzymes even in the presence of repressing concentrations of tryptophan. The anthranilate synthetase from one mutant was more sensitive to feedback inhibition by tryptophan than the enzyme from wild-type cells. The enzyme from the second mutant was comparatively resistant to feedback inhibition by tryptophan. Neither strain excreted tryptophan into the culture fluid. Tryptophan inhibits anthranilate synthetase from wild-type cells noncompetitively with respect to chorismate and uncompetitively with respect to glutamine. The Michaelis constants calculated for chorismate and glutamine are 7.6 x 10-5 M and 6.7 x 10-4 M, respectively. The molecular weights of the enzymes estimated by zonal centrifugation in sucrose and by gel filtration ranged from 24,000 to 89,000. With the possible exception of a tryptophan synthetase complex, there was no evidence for the existence of other enzyme aggregates. The data indicate that tryptophan synthesis is regulated by repression control of the relevant enzymes and by feedback inhibition of anthranilate synthetase. That this enzyme system more closely resembles that found in Bacillus than that found in enteric bacteria is discussed.

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“…Bio-Gel P-200 in the presence of 100 mM glutamine and 20 mM Tris-Cl, pH 7.2; the molecular weight was estimated at 90,000 (4). Interspecific complementation between B. subtilis and B. alvei AS components was not attempted, but is an experimental approach opened by these results.…”

Section: Fraction Numbermentioning

confidence: 99%

“…Prior to this study, the enzymes of this pathway in B. pumilus had not been studied at all. In extracts of B. alvei, the first enzyme of the pathway, anthranilate synthase (AS), had been reported to be quite unstable, and the second, anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase (PRT), undetectable (4). It had been reported that the last enzyme of the pathway, tryptophan synthetase (TS), could be stabilized by 30% glycerol (23).…”

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confidence: 99%

Enzymes of the Tryptophan Pathway in Three Bacillus Species

Hoch

Crawford

1973

J Bacteriol

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The tryptophan synthetic pathway was characterized in three species of Bacillus, B. subtilis, B. pumilus, and B. alvei. They share the common features of a pathway which is subject to tryptophan repression, contains no unexpected complexes among the five enzymes, exhibits dissociable anthranilate synthase enzymes which do not require phosphoribosyl transferase for amidetransfer activity, contains separate indoleglycerol phosphate synthase and phosphoribosylanthranilate isomerase enzymes, and contains similar tryptophan synthetase multimers. In looking at these characteristics in detail however, differences among the three species became apparent, as, for example, in the complementation observed between the a and 12 components of tryptophan synthetase, and the dissociation patterns of the large and small components of anthranilate synthase. The results demonstrate some pitfalls in attempting to compare multimeric enzymes in crude extracts from different organisms.

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Physiological and Kinetic Studies with Anthranilate Synthetase of Bacillus alvei

Cited by 15 publications

References 25 publications

Rapid Regulation of an Anthranilate Synthase Aggregate by Hysteresis

Rapid Regulation of an Anthranilate Synthase Aggregate by Hysteresis

Regulation of the Tryptophan Synthetic Enzymes in Clostridium butyricum

Enzymes of the Tryptophan Pathway in Three Bacillus Species

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