This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: S-adenosylmethionine biosynthesis
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis|
It has been said that no biological compound functions in as many different types of biological reactions as S-adenosyl-L-methionine (known as SAM or AdoMet). It is probably second only to ATP in the variety of reactions for which it serves as a cofactor. SAM is found in all living organisms, and fulfils three important roles:
* In transmethylation, SAM is the principal biological methyl donor.
* In transsulfuration, the sulfur atom of the SAM is converted via a series of enzymatic steps to cysteine, a precursor of taurine and glutathione, a major cellular anti-oxidant.
* In polyamine biosynthesis, SAM is the donor of aminopropyl groups.
The structure of SAM was first elucidated by Cantoni in 1951 [Cantoni51a]. The key to SAM's activity lies in the presence of the high energy sulfonium ion, which activates each of the attached carbons toward nucleophilic attack. In most cases, SAM reacts by transfer of the S-methyl group to a long list of possible acceptors in transmethylation reactions.
SAM is synthesized in the cytosol of every cell from L-methionine and ATP, in a reaction catalyzed by methionine adenosyltransferase. In animals, up to half of the daily intake of L-methionine is converted to SAM. In this unusual reaction, the adenosyl moiety of ATP is transferred to methionine, forming a sulfonium ion which is a high energy reagent that can easily transfer its methyl group to a large variety of acceptor substrates including nucleic acids, proteins, phospholipids, biologic amines, and a long list of small molecules [Lu00b].
Superpathways: L-methionine salvage cycle III , L-methionine salvage cycle II (plants) , L-methionine salvage cycle I (bacteria and plants) , S-adenosyl-L-methionine cycle I , aspartate superpathway , superpathway of S-adenosyl-L-methionine biosynthesis
Unification Links: EcoCyc:SAM-PWY
Peleman89: Peleman J, Boerjan W, Engler G, Seurinck J, Botterman J, Alliotte T, Van Montagu M, Inze D (1989). "Strong cellular preference in the expression of a housekeeping gene of Arabidopsis thaliana encoding S-adenosylmethionine synthetase." Plant Cell 1989;1(1);81-93. PMID: 2535470
Arifuzzaman06: Arifuzzaman M, Maeda M, Itoh A, Nishikata K, Takita C, Saito R, Ara T, Nakahigashi K, Huang HC, Hirai A, Tsuzuki K, Nakamura S, Altaf-Ul-Amin M, Oshima T, Baba T, Yamamoto N, Kawamura T, Ioka-Nakamichi T, Kitagawa M, Tomita M, Kanaya S, Wada C, Mori H (2006). "Large-scale identification of protein-protein interaction of Escherichia coli K-12." Genome Res 16(5);686-91. PMID: 16606699
Chattopadhyay91: Chattopadhyay MK, Ghosh AK, Sengupta S (1991). "Control of methionine biosynthesis in Escherichia coli K12: a closer study with analogue-resistant mutants." J Gen Microbiol 137(3);685-91. PMID: 2033383
Chiang77: Chiang PK, Cantoni GL (1977). "Activation of methionine for transmethylation. Purification of the S-adenosylmethionine synthetase of bakers' yeast and its separation into two forms." J Biol Chem 1977;252(13);4506-13. PMID: 194884
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Fu96: Fu Z, Hu Y, Markham GD, Takusagawa F (1996). "Flexible loop in the structure of S-adenosylmethionine synthetase crystallized in the tetragonal modification." J Biomol Struct Dyn 13(5);727-39. PMID: 8723769
Kamarthapu08: Kamarthapu V, Rao KV, Srinivas PN, Reddy GB, Reddy VD (2008). "Structural and kinetic properties of Bacillus subtilis S-adenosylmethionine synthetase expressed in Escherichia coli." Biochim Biophys Acta 1784(12);1949-58. PMID: 18634909
Komoto04: Komoto J, Yamada T, Takata Y, Markham GD, Takusagawa F (2004). "Crystal structure of the S-adenosylmethionine synthetase ternary complex: a novel catalytic mechanism of S-adenosylmethionine synthesis from ATP and Met." Biochemistry 43(7);1821-31. PMID: 14967023
Lasserre06: Lasserre JP, Beyne E, Pyndiah S, Lapaillerie D, Claverol S, Bonneu M (2006). "A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis." Electrophoresis 27(16);3306-21. PMID: 16858726
Lee97e: Lee JH, Chae HS, Lee JH, Hwang B, Hahn KW, Kang BG, Kim WT (1997). "Structure and expression of two cDNAs encoding S-adenosyl-L-methionine synthetase of rice (Oryza sativa L.)." Biochim Biophys Acta 1354(1);13-8. PMID: 9375784
LeGros00: LeGros HL, Halim AB, Geller AM, Kotb M (2000). "Cloning, expression, and functional characterization of the beta regulatory subunit of human methionine adenosyltransferase (MAT II)." J Biol Chem 275(4);2359-66. PMID: 10644686
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