ACETOLACTATE, AN EARLY INTERMEDIATE IN VALINE BIOSYNTHESIS<sup>1</sup>

Umbarger, H. E.; Brown, B. R.; Eyring, Edward J.

doi:10.1021/ja01568a088

Cited by 51 publications

(21 citation statements)

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“…7 ) : It has been reported that acetohydroxy acid synthetase from Salmonella typhimurium, Escherichia coli, and A. aerogenes, which catalyzes the formation of acetolactate and acetohydroxy butyrate, has a requirement for FAD [17,18,4]. This enzyme is inhibited by its end-product valine in these organisms [6,19,20].…”

Section: Discussionmentioning

confidence: 99%

The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

Malthe‐Sørenssen

Størmer

1970

European Journal of Biochemistry

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The pH 6 acetolactate-forming enzyme from Serratia mrcescens has been purified to homogeneity, and some of its characteristics have been described.Cocarboxylase and manganese have been completely removed from the enzyme. The addition of FAD to the enzyme did not stimulate the formation of acetolactate, and no FAD was released from the enzyme after trichloro-acetic acid treatment.The enzyme did not crystallize as the same enzyme from Aerobacter aerogenes does, but the kinetic properties of the enzyme are similar. The pH optimum in acetate is 6.0, and the enzyme activity is inhibited by phosphate and sulfate. These compounds cause sigmoidal kinetics, and apparent Michaelis kinetics are observed in acetate. This work was undertaken in order to purify the pH 6 acetolactate-forming enzyme from Serratia marcescens, and compare its properties with the same enzyme previously isolated from A . aerogenes.

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Section: Discussionmentioning

confidence: 99%

The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

Malthe‐Sørenssen

Størmer

1970

European Journal of Biochemistry

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“…enterica has an additional threonine dehydratase, TdcB, that catalyzes the same reaction as IlvA but is regulated differently and only expressed under anaerobic conditions (32,33 replaced with equimolar TdcB in the coupled assay. However, branched chain amino acid aminotransferase, (IlvE; EC 2.6.1.42) another PLP-dependent enzyme, was unable to substitute for IlvA when provided with either threonine or its natural substrate, isoleucine.…”

Section: Reconstitution Of Trpd-dependent Pra Formation In Vitro-mentioning

confidence: 99%

Members of the YjgF/YER057c/UK114 Family of Proteins Inhibit Phosphoribosylamine Synthesis in Vitro

Lambrecht¹,

Browne

Downs

2010

Journal of Biological Chemistry

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The YjgF/YER057c/UK114 family of proteins is highly conserved across all three domains of life and currently lacks a consensus biochemical function. Analysis of Salmonella enterica strains lacking yjgF has led to a working model in which YjgF functions to remove potentially toxic secondary products of cellular enzymes. Strains lacking yjgF synthesize the thiamine precursor phosphoribosylamine (PRA) by a TrpD-dependent mechanism that is not present in wild-type strains. Here, PRA synthesis was reconstituted in vitro with anthranilate phosphoribosyltransferase (TrpD), threonine dehydratase (IlvA), threonine, and phosphoribosyl pyrophosphate. TrpD-dependent PRA formation in vitro was inhibited by S. enterica YjgF and the human homolog UK114. Thus, the work herein describes the first biochemical assay for diverse members of the highly conserved YjgF/YER057c/UK114 family of proteins and provides a means to dissect the cellular functions of these proteins.

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“…CataboliC L-tbreornine dehydratase (EC 4.2.1.16;Umbarger & Brown, 1957) and L-threonine aldolase (EC 2.1.2.1; Morris, 1969) initiate dissimilation in other species. A sxirvey of a large number of isolates capable of growth on L-threonine as the sole or major source of carboti and nitrogen has revealed that the majority possessed inducibly synthesized L-threonine 3-dehydr6genase of high activity but low dehydratase aiid aldolase S. C. BELL AND J. M. TURNER Bacteria were maintained on nutrient broth and cultivated on semisynthetic media.…”

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confidence: 99%

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

Bell

Turner

1976

Biochemical Journal

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1. Isolates representing seven bacterial genera capable of growth on L-threonine medium, and possessing high L-threonine 3-dehydrogenase activity, were examined to elucidate the catabolic route. 2. The results of growth, manometric and enzymic experiments inddicated the catabolism of L-threonine by cleavage to acetyl-CoA plus glycine, the glycine being further metabolized via L-serine to pyruvate, in all cases. No evidence was obtained of a role for aminoacetone in threonine catabolismn or for the metabolism of glycine by the glycerate pathway. 3. 'Te properties of a number of key enzymes in Lthreonine catabolism were investigated. The inducibly formed L-threonine 3-dehydrogenase, purified from Corynebacterium sp. B6 to a specific activity of about 30-354umol of product formed/min per mg of protein, exhibited a sigmoid kinetic response to substrate concentration. The half-saturating concentration of substrate, [S]0.S, was 20mM and the Hill constant (h) Wvas 1.5. The Km for NAD+ was 0.8 mm. The properties ofthe enzyme were studied in cell-free extracts of other bacteria. 4. New assays for 2-amino-3-oxobutyrate-CoA ligase were devised. The Km for CoA was determined for the first time and found to be 0.14nmm at pH8, for the enzyme from Corynebacteriumf sp. B6. Evidence was obtained for the efficient linkage of the dehydrogenase and ligase enzymes. Cell-free extracts all possessed high activities of the inducibly formed ligase. 5. L-Serine hydroxymethyltransferase was formed constitutively by all isolates, whereas formation of the 'glycine-cleavage system' was generally induced by growth on L-threonine or glycine. The coenzyme requirements ofboth enzymes were established, and their linked activity in the production of L-serine from glycine was demonstrated by using extracts of Corynebacterium sp. B6. 6. L-Sernne dehydratase, purified from Corynebacterium sp. B6 to a specific activity of about 4pmol of product formed/min per mg of protein, was found to exhibit sigmoid kinetics with an [S]0.S of about 20mM and h = 1.4. Similar results were obtained with enzyme preparations from all isolates. The enzyme required Mg2+ for maximum activity, was different from the L-threonine dehydratase also detectable in extracts, and was induced by growth oh t-threonine or glycine.

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ACETOLACTATE, AN EARLY INTERMEDIATE IN VALINE BIOSYNTHESIS¹

Cited by 51 publications

References 0 publications

The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

Members of the YjgF/YER057c/UK114 Family of Proteins Inhibit Phosphoribosylamine Synthesis in Vitro

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

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ACETOLACTATE, AN EARLY INTERMEDIATE IN VALINE BIOSYNTHESIS1

Cited by 51 publications

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The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

The pH 6 Acetolactate‐Forming Enzyme from Serratia marcescens

Members of the YjgF/YER057c/UK114 Family of Proteins Inhibit Phosphoribosylamine Synthesis in Vitro

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

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ACETOLACTATE, AN EARLY INTERMEDIATE IN VALINE BIOSYNTHESIS¹