The enzymic formation of aminoacetone from threonine and its further metabolism

Green, Margaret L.; Elliott, William H.

doi:10.1042/bj0920537

Cited by 82 publications

(23 citation statements)

References 37 publications

(15 reference statements)

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“…Part of the work described here represents the first unambiguous demonstration that certain micro-organisms can metabolize aminoacetone (Higgins & Turner,I 966). It was previously pointed out by Green & Elliott (1964) that although preparations of some micro-organisms showed slight activity towards the amino ketone, its further metabolism at a significant rate had yet to be established. The recently reported metabolism of aminoacetone by a micro-organism similar to Arthrobacter globiformis, after growth on L-threonine (Green & Lewis, 1968), occurs at a rate only 5 % of those described here for pseudomonads.…”

Section: Discussionmentioning

confidence: 99%

“…been established that aminoacetone was metabolized by micro-organisms at a significant rate (Green & Elliott, 1964), and suggestions have been made that the amino ketone represents a waste product of no metabolic importance (Neuberger & Tait, 1962;McGilvray & Morris, 1966).…”

Section: J H I G G I N S M a P I C K A R D A N D J M T U R mentioning

confidence: 99%

“…It is possible that this 2-oxoaldehyde is an intermediate but that intact organisms are either impermeable or incapable of oxidizing it at the concentration tested. It is of interest that Green & Lewis (1968) have demonstrated the production of methylglyoxal from aminoacetone by suspensions of an Arthrobacter sp.…”

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confidence: 99%

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Aminoacetone Formation and Utilization by Pseudomonads Grown on DL-1-Aminopropan-2-ol

Higgins

Pickard

Turner

1968

Journal of General Microbiology

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SUMMARYPseudomonas sp. 8/1x isolated from soil and Pseudomonas sp. NCIB 8858 are capable of growth on DL-I-aminopropan-2-01 or aminoacetone as sole sources of carbon, nitrogen and energy. During growth on the amino alcohol, small amounts of aminoacetone initially accumulate in the medium but disappear during the early logarithmic phase. Aminoacetone accumulation is favoured by high pH and high growth-substrate concentrations.Washed suspensions of the pseudomonads grown on DL-I-aminopropan-2-01 accumulate aminoacetone when incubated with the amino alcohol in the presence of metabolic inhibitors, and rapidly utilize aminoacetone in their absence. Aminoacetone formation is optimal at about pH 10 in the presence or absence of the most effective inhibitor iodoacetate.Aminoacetone utilization occurs optimally at pH 7-7, the apparent X, for the amino ketone being about 0.1 mM. At an initial concn. of 1.0 m~, the rate of utilization is proportional to cell density up to at least 0.5 mg. dry wt organisms/ml. and is constant with time over almost the entire course of the reaction. The maximum rate of utilization is approximately I 50 mpmoleslmg. dry wt organisms/min. at 30°. The phenyl analogue 2'-aminoacetophenone is utilized at a comparable rate but 5-aminolaevulate is virtually unaffected. Anaerobic conditions and metabolic inhibitors prevent amino ketone utilization.Growth conditions markedly affect the ability of suspensions both to accumulate and utilize aminoacetone. Of the growth substrates tested, only L-threonine eaabled Pseudomonas sp. 8/1x to utilize aminoacetone, the rate being approx. 60% of that found after growth on DL-I-aminopropan-2-01The patterns of oxidation of possible intermediates of DL-I -aminopropan-2-01 catabolism are similar using washed organisms grown on either the amino alcohol or aminoacetone. Organisms grown on acetate plus glycine oxidize such compounds at relatively low rates. Methylglyoxal is not a substrate for either growth or oxidation. Comparison of the rates of oxygen uptake and aminoacetone utilization, and measurement of the total oxygen consumed, indicate about 70 % complete oxidation of the amino ketone by organisms grown on the amino alcohol.Similar maximum crop-sizes are obtained in media in which ammonium sulphate or different relative amounts of D-and L-I-aminopropan-2-01 serve as the sole sources of growth-limiting nitrogen.

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Section: Discussionmentioning

confidence: 99%

Section: J H I G G I N S M a P I C K A R D A N D J M T U R mentioning

confidence: 99%

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Aminoacetone Formation and Utilization by Pseudomonads Grown on DL-1-Aminopropan-2-ol

Higgins

Pickard

Turner

1968

Journal of General Microbiology

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“…This was carried out by a modification of the method described by Green & Elliott (1964). Reaction mixtures contained 250jumol of Tris/HCl buffer, pH8.6, lO,umol of NAD+, 300pmol of KCI, 0.2ml of enzyme preparation and 120jumol of L-threonine in a total volume of 1 ml.…”

Section: Enzyme Assaysmentioning

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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“…Threonine dehydrogenase (EC 1.1.1.103) is found in many bacteria (13,18,21,24,37,41) and in mammalian tissues (2,13,14,33,36,39). This enzyme catalyzes the NAD+-dependent oxidation of threonine to cx-amino-,-ketobutyrate (AKB).…”

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Structural and functional analysis of a cloned segment of Escherichia coli DNA that specifies proteins of a C4 pathway of serine biosynthesis

Ravnikar

Somerville

1987

J Bacteriol

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The plasmid pDR121 is a pBR322 derivative that contains a 3.7-kilobase-pair EcoRI fragment of DNA from the 81.2-min region of the Escherichia coli chromosome. The genomic insert encodes threonine dehydrogenase and at least one other protein. Several physical and kinetic properties of threonine dehydrogenase, overproduced in cells harboring pDR121, are identical to those of pure threonine dehydrogenase from a haploid mutant of E. coli K-12 that produces this enzyme constitutively. Tester strains with serB or glyA mutations harboring pDR121 are prototrophs. The ability to confer prototrophy on such tester strains is associated with elevated levels of threonine dehydrogenase. The functional roles of various segments of the 3.7-kilobase-pair insert of pDR121 were analyzed by constructing specific deletions and insertions. Certain subclones retained the ability to specify threonine dehydrogenase without conferring prototrophy on tester strains. This suggests that at least one other protein encoded within pDR121 plays an essential role in the conversion of threonine to serine.

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The enzymic formation of aminoacetone from threonine and its further metabolism

Cited by 82 publications

References 37 publications

Aminoacetone Formation and Utilization by Pseudomonads Grown on DL-1-Aminopropan-2-ol

Aminoacetone Formation and Utilization by Pseudomonads Grown on DL-1-Aminopropan-2-ol

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

Structural and functional analysis of a cloned segment of Escherichia coli DNA that specifies proteins of a C4 pathway of serine biosynthesis

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