[35] S-adenosylmethionine synthetase (methionine adenosyltransferase) (Escherichi coli)

Markham, George D.; Hafner, Edmund W.; Tabor, Celia White; Tabor, Herbert

doi:10.1016/s0076-6879(83)94037-5

Cited by 82 publications

(118 citation statements)

References 3 publications

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“…The K , values calculated are in good agreement with those reported in the literature for mammalian CI and y forms [20,22,23] and human lymphocyte AdoMet synthetase [19]. Both double-reciprocal plots showed good linearity indicating the absence of cooperativity, in agreement with the data reported for the enzyme from E. coli [17], human lymphocytes [19] and erythrocytes [16].…”

Section: Michaelis Constants and Inhibition Studiessupporting

confidence: 89%

“…This finding implies that inorganic tripolyphosphate could be an enzyme-bound intermediate which is cleaved by a tripolyphosphatase intrinsically associated with AdoMet synthetase [12-141. AdoMet synthetase is distributed in both prokaryotic and eukaryotic organisms [5,15, 161 and it has been purified to homogeneity from Escherichiu coli [17] [20,23, 241. There is a general agreement that the y form is the major, if not the only form, in normal nonhepatic tissues of rat and man [20,23, 251.…”

mentioning

confidence: 99%

“…This finding implies that inorganic tripolyphosphate could be an enzyme-bound intermediate which is cleaved by a tripolyphosphatase intrinsically associated with AdoMet synthetase [12-141. AdoMet synthetase is distributed in both prokaryotic and eukaryotic organisms [5,15,161 and it has been purified to homogeneity from Escherichiu coli [17], yeast [18], human lymphocytes [19], rat liver [20 -221 and rat kidney [23]. Several multiple isoforms of the enzyme with different kinetic regulatory and physical properties have been demonstrated in eukaryotes; two forms have been purified in yeast [18] and three isoforms, i.e.…”

mentioning

confidence: 99%

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S‐Adenosylmethionine synthetase in the thermophilic archaebacterium Sulfolobus solfataricus.

Porcelli¹,

Cacciapuoti²,

Cartenı́-Farina³

et al. 1988

European Journal of Biochemistry

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Two isoforms of methionine adenosyltransferase (S-adenosylmethionine synthetase), A and B, have been partially purified from Sulfolobus solfuturicus, a thermophilic archaebacterium optimally growing at 87 "C. The chromatographic procedure, involving hydrophobic chromatography on a phenyl-Sepharose column as a major step, results in 330-fold and 150-fold purification of adenosylmethionine synthetase A and B respectively. The apparent molecular masses, estimated by gel filtration, are 180 kDa for A and 75 kDa for B.The A and B isoforms follow Michaelis-Menten kinetics with apparent K , values of 10 pM nd 20 pM for L-methionine and of 50 pM and 150 pM for ATP respectively. Adenosylmethionine, a product of the reaction, acts as a powerful non-competitive inhibitor (Ki = 50 pM) of the A isoform while it inhibits only slightly the B isoform. Both isozymes exhibit tripolyphosphatase activity but only that associated with the form A is stimulated by 5 pM adenosylmethionine concentration. The two enzymes absolutely require a divalent cation for the activity, but are not affected by monovalent ions and reducing agents.The optimum temperature is 90°C and no significant loss of activity is observable after incubation of the two isoforms at 100 "C in the presence of ATP. The Arrhenius plots observed for both isozymes are biphasic, indicating different activation energies below and above 75 "C.The cytoplasmic levels of ATP, methionine and adenosylmethionine are evaluated.The metabolic importance of S-adenosylmethionine (AdoMet) in both eukaryotic and prokaryotic organisms is well known. Besides its major roles as methyl and aminopropyl donor, the sulfonium compound functions either as substrate or as modulator of a number of enzymatic systems [l -51. In contrast, only few data are available in the literature on the metabolism of AdoMet in archaebacteria [6, 71, which represent the third line of evolution, completely distinct from the eukaryotic and eubacterial lines [8].Recently, in halophilic and methanogenic archaebacteria, methylated DNA has been identified [9], but no data have been reported so far on the molecular features of the enzymes involved in the biosynthesis and metabolism of AdoMet in such microorganisms.In Sulfolobus solfuturicus, an extreme thermoacidophilic archaebacterium, optimally growing at 8 7 T , the role of AdoMet as methyl donor to proteins and as precursor of the symmetrical polyamines has been established [lo, 111.In eubacteria as well as in eukaryotes the synthesis of AdoMet from methionine and ATP is catalyzed by Ado- Met synthetase (ATP:L-methionine S-adenosyltransferase) through an unusual reaction in which the energy-rich sulfonium compound is formed by the complete dephosphorylation of ATP [12]. Pyrophosphate originating from the a and fi phosphates of ATP, and orthophosphate originating from the y phosphate, together represent the other products of the enzymatic reaction [12]. This finding implies that inorganic tripolyphosphate could be an enzyme-bound intermediate which is cleaved by a trip...

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Section: Michaelis Constants and Inhibition Studiessupporting

confidence: 89%

mentioning

confidence: 99%

“…This finding implies that inorganic tripolyphosphate could be an enzyme-bound intermediate which is cleaved by a tripolyphosphatase intrinsically associated with AdoMet synthetase [12-141. AdoMet synthetase is distributed in both prokaryotic and eukaryotic organisms [5,15,161 and it has been purified to homogeneity from Escherichiu coli [17], yeast [18], human lymphocytes [19], rat liver [20 -221 and rat kidney [23]. Several multiple isoforms of the enzyme with different kinetic regulatory and physical properties have been demonstrated in eukaryotes; two forms have been purified in yeast [18] and three isoforms, i.e.…”

mentioning

confidence: 99%

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S‐Adenosylmethionine synthetase in the thermophilic archaebacterium Sulfolobus solfataricus.

Porcelli¹,

Cacciapuoti²,

Cartenı́-Farina³

et al. 1988

European Journal of Biochemistry

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“…1) in a reaction which takes advantage of all three ATP phosphates to produce the reactive sulfonium (Markham et al, 1980):…”

Section: Introductionmentioning

confidence: 99%

Cell division, one-carbon metabolism and methionine synthesis in a metK-deficient Escherichia coli mutant, and a role for MmuM

2013

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An E. coli K-12 mutant deficient in S-adenosylmethionine (SAM) synthesis, i.e DmetK, but expressing a rickettsial SAM transporter, can grow in glucose minimal medium if provided with both SAM and methionine. It uses the externally provided (R)-enantiomer of SAM as methyl donor to produce most but not all of its methionine, by methylation of homocysteine catalysed by homocysteine methyltransferase (MmuM). The DmetK cells are also altered in growth and are twice as long as those of the parent strain. When starved of SAM, the mutant makes a small proportion of very long cells suggesting a role of SAM and of methylation in the onset of crosswall formation.

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“…PfSAMS could form dimers in a manner almost identical to that seen in E. coli SAMS, but PfSAMS cannot form homotetramers as seen in E. coli SAMS [34]. Figure 3(b) shows the degree of amino acid conservation between E. coli SAMS and PfSAMS for residues in the dimer interface.…”

Section: Figure 2 Cladogram For the Phylogenetic Relationship Of Samsmentioning

confidence: 93%

Molecular characterization of Plasmodium falciparum S-adenosylmethionine synthetase

Chiang

Chamberlin

Nicholson

et al. 1999

Biochemical Journal

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S-Adenosylmethionine (AdoMet) synthetase (SAMS: EC 2.5.1.6) catalyses the formation of AdoMet from methionine and ATP. We have cloned a gene for Plasmodium falciparum AdoMet synthetase (PfSAMS) (GenBank accession no. AF097923), consisting of 1209 base pairs with no introns. The gene encodes a polypeptide (PfSAMS) of 402 amino acids with a molecular mass of 44844 Da, and has an overall base composition of 67% A+T. PfSAMS is probably a single copy gene, and was mapped to chromosome 9. The PfSAMS protein is highly homologous to all other SAMS, including a conserved motif for the phosphate-binding P-loop, HGGGAFSGKD, and the signature hexapeptide, GAGDQG. All the active-site amino acids for the binding of ADP, Pi and metal ions are similarly preserved, matching entirely those of human hepatic SAMS and Escherichia coli SAMS. Molecular modelling of PfSAMS guided by the X-ray crystal structure of E. coli SAMS indicates that PfSAMS binds ATP/Mg2+ in a manner similar to that seen in the E. coli SAMS structure. However, the PfSAMS model shows that it can not form tetramers as does E. coli SAMS, and is probably a dimer instead. There was a differential sensitivity towards the inhibition by cycloleucine between the expressed PfSAMS and the human hepatic SAMS with Ki values of 17 and 10 mM, respectively. Based on phylogenetic analysis using protein parsimony and neighbour-joining algorithms, the malarial PfSAMS is closely related to SAMS of other protozoans and plants.

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[35] S-adenosylmethionine synthetase (methionine adenosyltransferase) (Escherichi coli)

Cited by 82 publications

References 3 publications

S‐Adenosylmethionine synthetase in the thermophilic archaebacterium Sulfolobus solfataricus.

S‐Adenosylmethionine synthetase in the thermophilic archaebacterium Sulfolobus solfataricus.

Cell division, one-carbon metabolism and methionine synthesis in a metK-deficient Escherichia coli mutant, and a role for MmuM

Molecular characterization of Plasmodium falciparum S-adenosylmethionine synthetase

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