Abstract
A tryptophan-requiring auxotroph of Agmenellum quadruplicatum strain BG1, a species of blue-green bacteria, was isolated by means of a nitrosoguanidine-penicillin procedure. Its growth characteristics were determined, and the enzymological block was identified in the A activity of tryptophan synthetase. Starvation of the auxotroph for tryptophan resulted in the derepression of the synthesis of all five enzymes. The first four enzymes derepressed 2- to 3-fold, and tryptophan synthetase B derepressed 20-fold. In the parental prototroph, BG1, anthranilate synthetase was active in crude extracts with ammonia as the amino donor reactant, but not with glutamine.
MeSH terms
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Anthranilate Synthase / metabolism
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Carbohydrate Epimerases / metabolism
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Carboxy-Lyases / metabolism
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Cell-Free System
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Cyanobacteria / enzymology
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Cyanobacteria / growth & development
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Cyanobacteria / isolation & purification
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Cyanobacteria / metabolism*
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Enzyme Repression
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Glycerophosphates
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Mutagens
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Mutation*
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Nitrosoguanidines
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Penicillin G
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Pentosyltransferases / metabolism
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Spectrometry, Fluorescence
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Tryptophan / metabolism*
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Tryptophan Synthase / metabolism
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ortho-Aminobenzoates
Substances
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Glycerophosphates
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Mutagens
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Nitrosoguanidines
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ortho-Aminobenzoates
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Tryptophan
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Pentosyltransferases
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Carboxy-Lyases
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Anthranilate Synthase
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Tryptophan Synthase
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Carbohydrate Epimerases
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Penicillin G