S-Methylmethionine Metabolism in Escherichia coli Export

@article{citeulike:6043620, abstract = {Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group from S-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed that Escherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants in yagD which also possess defects in metE and metH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in a metE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfD and yagD products appear to reside in the acquisition of S-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.}, author = {Thanbichler, Martin and Neuhierl, Bernhard and Bock, August}, citeulike-article-id = {6043620}, citeulike-linkout-0 = {http://jb.asm.org/content/181/2/662.abstract}, citeulike-linkout-1 = {http://jb.asm.org/content/181/2/662.full.pdf}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/9882684}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=9882684}, day = {15}, journal = {J. Bacteriol.}, keywords = {coli, escherichia, homocysteine, metabolism, s-methylmethionine}, month = {January}, number = {2}, pages = {662--665}, posted-at = {2009-10-30 16:38:24}, priority = {2}, title = {S-Methylmethionine Metabolism in Escherichia coli}, url = {http://jb.asm.org/content/181/2/662.abstract}, volume = {181}, year = {1999} }

TY - JOUR ID - citeulike:6043620 L3 - citeulike-article-id:6043620 N2 - Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group from S-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed that Escherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants in yagD which also possess defects in metE and metH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in a metE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfD and yagD products appear to reside in the acquisition of S-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis. IS - 2 JF - J. Bacteriol. EP - 665 TI - S-Methylmethionine Metabolism in Escherichia coli VL - 181 SP - 662 KW - coli KW - escherichia KW - homocysteine KW - metabolism KW - s-methylmethionine AU - Thanbichler, Martin AU - Neuhierl, Bernhard AU - Bock, August PY - 1999/01/15/ UR - http://jb.asm.org/content/181/2/662.abstract ER -