5-methylthioribose as a precursor of the carbon chain of methionine

Shapiro, Stuart; Barrett, Annabella

doi:10.1016/0006-291x(81)91521-7

Cited by 54 publications

(16 citation statements)

References 17 publications

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“…In mammalian tissue, MTA is directly converted to MTR-1-P by MTA phosphorylase (21) and, therefore, the action of MTR kinase is not required. MTR kinase activity has also been found in Enterobacter aerogenes (9), an organism shown to recycle MTA to methionine via a similar pathway (18). Conversely, we have not detected MTR kinase activity in extracts from Escherichia coli.…”

contrasting

confidence: 41%

Intermediates in the Recycling of 5-Methylthioribose to Methionine in Fruits

Kushad¹,

Richardson²,

Ferro³

1983

Plant Physiol.

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The recycling of 5-methylthioribose (MTR) to methionine in avocado (Persca americana Mill, cv Hass) and tomato (Lycopersicum escukxtum Mill, cv unknown) was examined. 1 CH31MTR was not metabolized in cell free extract from avocado fruit. Either I'4CH3IMTR plus ATP or [4CH315-methylthioribose-l-phosphate (MTR-1-P) alone, however, were metabolized to two new products by these extracts. MTR kinase activity has previously been detected in these fruit extracts. These data indicate that MTR must be converted to MTR-1-P by MTR kinase before further metabolism can occur. The products of MTR-1-P metabolism were tentatively identified as a-keto-'y-methylthiobutyric acid (a-KMB) and a-hydroxy-'y-methylthiobutyric acid (a-HMB) by chromatography in several solvent systems. I3SJa-KMB was found to be further metabolized to methionine and a-HMB by these extracts, whereas a-HMB was not.However, a-HMB inhibited the conversion of a-KMB to methionine.Both IU-14Cia-KMB and IU-'4qmethionine, but not were converted to ethylene in tomato pericarp tissue. In addition, aminoethoxyvinylglycine inhibited the conversion of a-KMB to ethylene. These data suggest that the recycling pathway leading to ethylene is MTR -. MTR-1-P -_ a-KMB -_ methionine -_ S-adenosylmethionine -_ 1-aminocyclopropane-l-carboxylic acid _ ethylene.

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confidence: 41%

Intermediates in the Recycling of 5-Methylthioribose to Methionine in Fruits

Kushad¹,

Richardson²,

Ferro³

1983

Plant Physiol.

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“…Adenine can enter the pool ofadenine nucleotides through the action ofadenine phosphoribosyltransferase, but the metabolic fate of MTR remained obscure. As was established earlier, the methylthio group of MTA (MTR) can be incorporated back into methionine (1,17,21) and recently it has been demonstrated in yeast (20), rat liver (4,22), Enterobacter aerogenes (19), apple (25), and tomato (24) tissues that MTA (MTR) furnishes both the methylthio group and the four-carbon chain of methionine. In partially fractionated rat liver homogenates, the MTR-1-P proved to be the compound which enters the novel pathway of methionine synthesis (4,22) and in cell-free extracts of E. aerogenes where, as mentioned above, MTA is degraded hydrolytically (7), the first step in the pathway is the phosphorylation of MTR by a specific 5-methylthioribose kinase (8) yielding MTR-1-P.…”

Section: Ch3s Ch3smentioning

confidence: 84%

Plant 5-Methylthioribose Kinase

Guranowski¹

1983

Plant Physiol.

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Activity of 5-methylthioribose kinase, the enzyme which catalyzes the ATP-dependent formation of 1-phospho-5-methylthioribose, has been revealed in the extracts from various higher plant species. AMmost 2,000-foldpurfied enzyme has been obtained from yellow lupin (Lupinus luates L. cv Topaz) seed extract. The nucleoside does not accumulate in cells and is effectively degraded. In animals (16), Euglena gracilis (14), fungi (12), and the thermophylic bacterium Caldariella acidophila (6), MTA is cleaved phosphorolytically, yielding adenine and MTR-l-P (Formula II), whereas in other bacteria (7, 23) and in plants (5, 1 1) it undergoes hydrolysis yielding adenine and MTR. Adenine can enter the pool ofadenine nucleotides through the action ofadenine phosphoribosyltransferase, but the metabolic fate of MTR remained obscure. As was established earlier, the methylthio group of MTA (MTR) can be incorporated back into methionine (1,17,21) and recently it has been demonstrated in yeast (20), rat liver (4,22), Enterobacter aerogenes (19), apple (25), and tomato (24) tissues that MTA (MTR) furnishes both the methylthio group and the four-carbon chain of methionine. In partially fractionated rat liver homogenates, the MTR-1-P proved to be the compound which enters the novel pathway of methionine synthesis (4, 22) and in cell-free extracts of E. aerogenes where, as mentioned above, MTA is degraded hydrolytically (7), the first step in the pathway is the phosphorylation of MTR by a specific 5-methylthioribose kinase (8) yielding MTR-1-P.So far, the biochemical steps of the conversion of MTR to methionine in plants have not been shown. Yung et al. (25) working with apple plugs were not able to detect MTR-1-P. The lack of accumulation of a given metabolite in the tissue, however, does not preclude the possibility that the compound may be synthesized but undergoes rapid transformation. Here, evidence is presented that, in higher plants, MTR-1-P may be an intermediate on the pathway leading from MTR to methionine, since a specific 5-methylthioribose kinase occurs in the organisms. The purification procedure and characterization of the enzyme from yellow lupin seeds are described. MATERIALS AND METHODS

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“…That 5-methylthioribose 1-phosphate is an intermediate in the biosynthesis of methionine has been demonstrated in Enterobacter aerogenes (Shapiro & Barrett, 1981) and in rat liver (Backlund et al, 1982). To determine if this was the case for S. cereuisiae, extracts of strain 221 8A were prepared as for our earlier studies with [methyl-14C] [ 14C]methylthiobutyrate with cell-free extracts.…”

Section: Metabolism Of [ 4c]methylthioribose I-phosphate In Cell-freementioning

confidence: 97%

“…Backlund & Smith (1981) reported that the primary function of MTA in rat liver extracts was the formation of methionine, and that the pathway by which this takes place involves modifications in the ribose portion of the molecule. Shapiro & Barrett (1981) …”

Section: Introductionmentioning

confidence: 99%

The Metabolism of 5'-Methylthioadenosine and 5-Methylthioribose 1-Phosphate in Saccharomyces cerevisiae

Marchitto¹,

Ferro²

1985

Microbiology

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~ ~~Cordycepin sensitive mutants of Saccharornyces cerevisiae, which are permeable to 5'-deoxy-5'-methylthioadenosine (MTA), were used to study the fate of the methylthioribose carbons of this purine nucleoside. Evidence is presented for the recycling of the methylthio group and part of the ribose portion of MTA in a biosynthetic pathway which leads to the synthesis of methionine.The main pathway involves the phosphorylytic cleavage of MTA by MTA phosphorylase yielding 5-methylthioribose 1 -phosphate and adenine as products. Loss of the phosphate group of 5-methylthioribose 1-phosphate, concurrent with the rearrangement of the ribose carbons, leads to the synthesis of 2-keto-4-methylthiobutyric acid. In the final step of the sequence, 2-keto-4-methylthiobutyric acid is converted to methionine via transamination. Several compounds not directly associated with the biosynthesis of methionine were also isolated. These compounds, which may arise through the degradation of intermediates in the pathway, were : 5'-methylthioinosine, a deaminated catabolite of MTA ; 5-methylthioribose, a result of the p hosp horylysis of 5-met hylt hiori bose 1 -phosphate, and 3-met hylthiopropionalde hyde, 3-methylthiopropionic acid and 2-hydroxy-4-methylthiobutyric acid, all arising from the catabolism of 2-ke to-4-met hylt hiobu tyric acid.

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5-methylthioribose as a precursor of the carbon chain of methionine

Cited by 54 publications

References 17 publications

Intermediates in the Recycling of 5-Methylthioribose to Methionine in Fruits

Intermediates in the Recycling of 5-Methylthioribose to Methionine in Fruits

Plant 5-Methylthioribose Kinase

The Metabolism of 5'-Methylthioadenosine and 5-Methylthioribose 1-Phosphate in Saccharomyces cerevisiae

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