Disease relevance of S-methylmethionine

• A model system was set up in E. coli which demonstrated that expression of the plant and, although to a much lesser degree, of the bacterial methyltransferase gene increases selenium tolerance and strongly reduces unspecific selenium incorporation into proteins, provided that S-methylmethionine is present in the medium [1].

High impact information on S-methylmethionine

• The increase in free Met and S-methylmethionine levels in these mutants, together with in vitro substrate specificity, strongly implicate BCAT4 in catalysis of the initial deamination of Met to 4-methylthio-2-oxobutyrate [2].
• Transport of sulfonium compounds. Characterization of the s-adenosylmethionine and s-methylmethionine permeases from the yeast Saccharomyces cerevisiae [3].
• The methylation product of enzyme I was identified as S-methylmethionine and that of enzyme II as NG-monomethylarginine [4].
• Insertional inactivation of the methionine s-methyltransferase gene eliminates the s-methylmethionine cycle and increases the methylation ratio [5].
• Constitutive overexpression of cystathionine gamma-synthase in Arabidopsis leads to accumulation of soluble methionine and S-methylmethionine [6].

Biological context of S-methylmethionine

• Acid hydrolysis of dehulled soybean meal (SBM) and corn gluten meal (CGM) followed by chromatographic amino acid analysis (ninhydrin detection) revealed substantial quantities of S-methylmethionine (SMM) in both ingredients (1.65 g SMM/kg SBM; 0.5 g SMM/kg CGM) [7].

Anatomical context of S-methylmethionine

• DMSP is known to be synthesized in the chloroplast from S-methylmethionine (SMM) imported from the cytosol, but the sizes of the chloroplastic and extrachloroplastic pools of these compounds are unknown [8].
• The conversion rate from 14 C-cholesterol to its 7 alpha-hydroxylated metabolites was studied in the microsome system prepared from mice liver with the pretreatment of S-methylmethionine (MMSC) [9].

Associations of S-methylmethionine with other chemical compounds

• Angiosperms synthesize S-methylmethionine (SMM) from methionine (Met) and S-adenosylmethionine (AdoMet) in a unique reaction catalyzed by Met S-methyltransferase (MMT) [10].
• YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate [11].
• Effects of S-methylmethionine (vitamin U) on experimental nephrotic hyperlipidemia [12].
• Surprisingly, transformed Arabidopsis plants exhibited a modest decrease in methionine content (35% reduction of the wild-type level) but a seven-fold decrease in the soluble pool of S-methylmethionine (SMM), a compound that plays a major role in storage and transport of reduced sulphur and labile methyl moieties [13].

Gene context of S-methylmethionine

• Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein [11].
• (Compositae) the first intermediate in DMSP biosynthesis has been shown to be S-methylmethionine (SMM) (A.D. Hanson, J. Rivoal, L. Paquet, D.A. Gage [1994] Plant Physiol 105: 103-110) [14].

References