S-Adenosylmethionine synthetase from Escherichia coli.

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

doi:10.1016/s0021-9258(19)70530-4

Cited by 226 publications

(126 citation statements)

References 35 publications

Supporting

Mentioning

114

Contrasting

Order By: Relevance

“…Assay of SAM synthetase. SAM synthetase activity was assayed by using "4C-labeled methionine and a modification of the method by Markham et al (11), which had been used for Escherichia coli (6). To prepare a crude cell extract, cells were grown in 200 ml of llv mnedium from a low inoculum (OD6w = 0.01) at 33, 37, or 43°C.…”

Section: Methodsmentioning

confidence: 99%

“…Selenomethionine is converted by SAM synthetase into the corresponding SAM analog in E. coli (11), yeast (4), and rat liver (15), and ethionine is converted to 5-adenosylethionine in yeast (18), rat liver (15), and inefficiently (Km = 3.3 mM) in E. coli (D. G. Markham, C. W. Tabor, and H. Tabor, personal communication). As some of the ethionine-resistant mutants isolated in E. coli have an altered SAM synthetase (11), we isolated such mutants in B. subtilis.…”

Section: Spontaous Sporulato Enhanced By Aminomentioning

confidence: 99%

See 1 more Smart Citation

A decrease in S-adenosylmethionine synthetase activity increases the probability of spontaneous sporulation

Ochi¹,

Freese²

1982

J Bacteriol

View full text Add to dashboard Cite

Starting with a relaxed (relA) strain, mutants with reduced activity of adenosine triphosphate:L-methionine S-adenosyl transferase (EC 2.5.1.6; SAM synthetase) were isolated in Bacillus subtilis. One such mutant (gene symbol metE1) had only 3% of the normal SAM synthetase activity but grew almost as well as the parent strain. Another mutant was isolated (gene symbol spdC1) as being able to sporulate continually at a high frequency; it had one-half the normal SAM synthetase activity at 33 degrees C. Both mutants continually and spontaneously entered spore development at a higher frequency than the parent strain in a medium containing excess glucose, ammonium ions, and phosphate. Sporulation was prevented by a high concentration of SAM (1 mM or more) or by the combination of adenosine and methionine (0.5 mM or more each), both of which are precursors of SAM. In contrast to this continual increase in the spore titer, addition of decoyinine, an inhibitor of GMP synthetase, rapidly initiated massive sporulation. Various amino acid analogs also induced sporulation in the relA strain, the methionine analogs ethionine and selenomethionine being most effective.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Spontaous Sporulato Enhanced By Aminomentioning

confidence: 99%

A decrease in S-adenosylmethionine synthetase activity increases the probability of spontaneous sporulation

Ochi¹,

Freese²

1982

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…Accordingly, we investigated whether differences between the native oligomeric states of either eMAT or hMAT2A underlie their different substrate specificity. We used the NTP analogues 33 .…”

Section: The Molecular Basis For Mat Specificitymentioning

confidence: 99%

“…structure to 2.5 Å resolution. Imido-NTP analogs have been used as partial inhibitors of MAT because, while they are still substrates for the first methionine transfer step and form the various SNM products, the imido-linkage between the β−γ phosphate units prevents hydrolysis of the triphosphate moiety 33 . Triphosphate hydrolysis is thought to provide energy for active site loop (residues 113-131 in hMAT2A, 98-108 in eMAT) opening and product release 28,32 .…”

Section: The Molecular Basis For Mat Specificitymentioning

confidence: 99%

Substrate dynamics contribute to enzymatic specificity in human and bacterial methionine adenosyltransferases

Gade

Tan

Damry

et al. 2021

Preprint

View full text Add to dashboard Cite

Protein conformational change can facilitate the binding of non-cognate substrates and underlie promiscuous activities. However, the contribution of substrate conformational dynamics to this process is comparatively poorly understood. Here we analyse human (hMAT2A) and Escherichia coli (eMAT) methionine adenosyltransferases that have identical active sites but different substrate specificity. In the promiscuous hMAT2A, non-cognate substrates bind in a stable conformation to allow catalysis. In contrast, non-cognate substrates rarely sample stable productive binding modes in eMAT owing to increased mobility of an active site loop. Different cellular concentrations of substrate likely drove the evolutionary divergence of substrate specificity in these orthologs. The observation of catalytic promiscuity in hMAT2A led to the detection of a new human metabolite, methyl thioguanosine, that is produced at elevated level in a cancer cell line. This work establishes that identical active sites can result in different substrate specificity owing to the combined effects of both enzyme and substrate dynamics.

show abstract

“…We also observed no SAM formation with AMP or ADP. Nature uses the same route to SAM biosynthesis, using ATP and giving triphosphate as the leaving group, and SAM synthetase also requires divalent cations, typically Mg 2+ (Scheme a, route I) . Furthermore, to overcome the reversibility of the reaction, SAM synthetases hydrolyze the triphosphate to orthophosphate and pyrophosphate …”

Section: Figurementioning

confidence: 99%

Spontaneous Emergence of S‐Adenosylmethionine and the Evolution of Methylation

Laurino

Tawfik

2016

Angewandte Chemie

View full text Add to dashboard Cite

S‐Adenosylmethionine (SAM) is an essential methylation cofactor. The origins of SAM methylation are complex, seemingly demanding the simultaneous emergence of an enzyme that makes SAM and enzyme(s) that utilize it. We report that both ATP and adenosine spontaneously react with methionine to yield SAM, thus suggesting that SAM could have emerged by chance. SAM methylation thus exemplifies how metabolites and pathways can co‐emerge through the gradual recruitment of individual enzymes in reverse order.

show abstract

S-Adenosylmethionine synthetase from Escherichia coli.

Cited by 226 publications

References 35 publications

A decrease in S-adenosylmethionine synthetase activity increases the probability of spontaneous sporulation

A decrease in S-adenosylmethionine synthetase activity increases the probability of spontaneous sporulation

Substrate dynamics contribute to enzymatic specificity in human and bacterial methionine adenosyltransferases

Spontaneous Emergence of S‐Adenosylmethionine and the Evolution of Methylation

Contact Info

Product

Resources

About