Sulfonium Ion Condensation: The Burden Borne by SAM Synthetase

Biochemistry ◽  
2018 ◽  
Vol 57 (26) ◽  
pp. 3549-3551 ◽  
Author(s):  
Charles A. Lewis ◽  
Richard Wolfenden
Keyword(s):  
Sam Synthetase

scholarly journals Lowering S-Adenosylmethionine Levels inEscherichia coli Modulates C-to-T Transition Mutations

2001 ◽  
Vol 183 (3) ◽  
pp. 921-927 ◽  
Author(s):  
Georgina Macintyre ◽  
C. Victoria Atwood ◽  
Claire G. Cupples
Keyword(s):  
Escherichia Coli ◽  
Dna Methylation ◽  
Genomic Dna ◽  
Synthetase Activity ◽  
Inescherichia Coli ◽  
Genome Methylation ◽  
Sam Synthetase ◽  
Methyl Cytosine

ABSTRACT Deoxycytosine methylase (Dcm) enzyme activity causes mutagenesis in vitro either directly by enzyme-induced deamination of cytosine to uracil in the absence of the methyl donor,S-adenosylmethionine (SAM), or indirectly through spontaneous deamination of [5-methyl]cytosine to thymine. Using a Lac reversion assay, we investigated the contribution of the first mechanism to Dcm mutagenesis in vivo by lowering the levels of SAM.Escherichia coli SAM levels were lowered by reducing SAM synthetase activity via the introduction of a metK84 allele or by hydrolyzing SAM using the bacteriophage T3 SAM hydrolase. ThemetK84 strains exhibited increased C-to-T mutagenesis. Expression of the T3 SAM hydrolase gene, under the control of the arabinose-inducible PBAD promoter, effectively reduced Dcm-mediated genomic DNA methylation. However, increased mutagenesis was not observed until extremely high arabinose concentrations were used, and genome methylation at Dcm sites was negligible.

scholarly journals Microarray Analysis Reveals S-Adenosylmethionine (SAM) Synthetase Involvement in Salt Tolerance of Cyanidioschyzon merolae

CYTOLOGIA ◽  
2008 ◽  
Vol 73 (3) ◽  
pp. 341-368 ◽  
Author(s):  
Takayuki Sakajiri ◽  
Keita Asano ◽  
Shunsuke Hirooka ◽  
Kosuke Tashiro ◽  
Osami Misumi ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Microarray Analysis ◽  
Cyanidioschyzon Merolae ◽  
Sam Synthetase

Structural and functional characterization of S-adenosylmethionine (SAM) synthetase from Pichia ciferrii

2011 ◽  
Vol 35 (1-2) ◽  
pp. 173-181 ◽  
Author(s):  
Sangyoung Yoon ◽  
Wonkyu Lee ◽  
Minsoo Kim ◽  
T. Doohun Kim ◽  
Yeonwoo Ryu
Keyword(s):  
Functional Characterization ◽  
Sam Synthetase

scholarly journals Identification of a Mutation in the Bacillus subtilis S-Adenosylmethionine Synthetase Gene That Results in Derepression of S-Box Gene Expression

2006 ◽  
Vol 188 (10) ◽  
pp. 3674-3681 ◽  
Author(s):  
Brooke A. McDaniel ◽  
Frank J. Grundy ◽  
Vineeta P. Kurlekar ◽  
Jerneja Tomsic ◽  
Tina M. Henkin
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Rna Structure ◽  
Synthetase Activity ◽  
Gene Encoding ◽  
Sam Synthetase ◽  
Transcription In Vitro ◽  
Adenosylmethionine Synthetase

ABSTRACT Genes in the S-box family are regulated by binding of S-adenosylmethionine (SAM) to the 5′ region of the mRNA of the regulated gene. SAM binding was previously shown to promote a rearrangement of the RNA structure that results in premature termination of transcription in vitro and repression of expression of the downstream coding sequence. The S-box RNA element therefore acts as a SAM-binding riboswitch in vitro. In an effort to identify factors other than SAM that could be involved in the S-box regulatory mechanism in vivo, we searched for trans-acting mutations in Bacillus subtilis that act to disrupt repression of S-box gene expression during growth under conditions where SAM pools are elevated. We identified a single mutant that proved to have one nucleotide substitution in the metK gene, encoding SAM synthetase. This mutation, designated metK10, resulted in a 15-fold decrease in SAM synthetase activity and a 4-fold decrease in SAM concentration in vivo. The metK10 mutation specifically affected S-box gene expression, and the increase in expression under repressing conditions was dependent on the presence of a functional transcriptional antiterminator element. The observation that the mutation identified in this search affects SAM production supports the model that the S-box RNAs directly monitor SAM in vivo, without a requirement for additional factors.

scholarly journals EXPRESSION OF ETHYLENE BIOSYNTHETIC PATHWAY mRNAs DURING CARNATION FLOWER SENESCENCE

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 580b-580
Author(s):  
William R. Woodson ◽  
Ky Young Park ◽  
Paul Larsen ◽  
Hong Wang
Keyword(s):  
Biosynthetic Pathway ◽  
Dianthus Caryophyllus ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Molecular Probes ◽  
Flower Senescence ◽  
Mrna Levels ◽  
Petal Senescence ◽  
Sam Synthetase ◽  
Carnation Flower

The senescence of carnation (Dianthus caryophyllus L.) flower petals is associated with increased synthesis of the phytohormone ethylene. This ethylene serves to initiate and regulate the processes of programmed cell death. We are using molecular approaches to study the regulation of ethylene biosynthesis in various floral organs during development and senescence of flowers. We have isolated and cloned mRNAs which encode the ethylene biosynthetic pathway enzymes s-adenosylmethionine (SAM) synthetase, 1-aminocyclopropane-1-carboxylate (ACC) synthase and the ethylene forming enzyme (EFE) from carnation flower petals. These cDNAs have been used as molecular probes to determine the steady-state mRNA levels of these transcripts in senescing flowers. The increase in ethylene associated with petal senescence is accompanied by a dramatic increase in the abundance of transcripts for both ACC synthase and EFE. In striking contrast, the level of SAM synthetase mRNA decreases significantly with the onset of petal senescence. Genomic DNA Southern blots reveal both ACC synthase and EFE are encoded by multigene families. We have recently isolated several genomic clones from carnation which represent different ACC synthase genes. The structure and organization of these gene will be presented.

scholarly journals A complex interplay between SAM synthetase and the epigenetic regulator SIN3 controls metabolism and transcription

2019 ◽  
Vol 295 (2) ◽  
pp. 375-389 ◽  
Author(s):  
Mengying Liu ◽  
Nirmalya Saha ◽  
Ambikai Gajan ◽  
Nadia Saadat ◽  
Smiti V. Gupta ◽  
...  
Keyword(s):  
Epigenetic Regulation ◽  
High Performance ◽  
Metabolic Enzyme ◽  
Rna Seq ◽  
Catabolic Genes ◽  
Chromatin Regulator ◽  
Sam Synthetase ◽  
Wide Range ◽  
Epigenetic Regulator ◽  
The Relationship

The SIN3 histone-modifying complex regulates the expression of multiple methionine catabolic genes, including SAM synthetase (Sam-S), as well as SAM levels. To further dissect the relationship between methionine catabolism and epigenetic regulation by SIN3, we sought to identify genes and metabolic pathways controlled by SIN3 and SAM synthetase (SAM-S) in Drosophila melanogaster. Using several approaches, including RNAi-mediated gene silencing, RNA-Seq– and quantitative RT-PCR–based transcriptomics, and ultra-high-performance LC-MS/MS– and GC/MS–based metabolomics, we found that, as a global transcriptional regulator, SIN3 impacted a wide range of genes and pathways. In contrast, SAM-S affected only a narrow range of genes and pathways. The expression and levels of additional genes and metabolites, however, were altered in Sin3A+Sam-S dual knockdown cells. This analysis revealed that SIN3 and SAM-S regulate overlapping pathways, many of which involve one-carbon and central carbon metabolisms. In some cases, the factors acted independently; in some others, redundantly; and for a third set, in opposition. Together, these results, obtained from experiments with the chromatin regulator SIN3 and the metabolic enzyme SAM-S, uncover a complex relationship between metabolism and epigenetic regulation.

scholarly journals The U6 snRNA m 6 A Methyltransferase METTL16 Regulates SAM Synthetase Intron Retention

Cell ◽  
2017 ◽  
Vol 169 (5) ◽  
pp. 824-835.e14 ◽  
Author(s):  
Kathryn E. Pendleton ◽  
Beibei Chen ◽  
Kuanqing Liu ◽  
Olga V. Hunter ◽  
Yang Xie ◽  
...  
Keyword(s):  
Intron Retention ◽  
U6 Snrna ◽  
Sam Synthetase

scholarly journals Influence of S-Adenosylmethionine Pool Size on Spontaneous Mutation, Dam Methylation, and Cell Growth ofEscherichia coli

1999 ◽  
Vol 181 (21) ◽  
pp. 6756-6762 ◽  
Author(s):  
Lauren M. Posnick ◽  
Leona D. Samson
Keyword(s):  
Alkylating Agent ◽  
Spontaneous Mutation ◽  
Dna Alkylation ◽  
Mutation Rates ◽  
E Coli ◽  
Sam Synthetase ◽  
Dam Methylation ◽  
Transition Mutation ◽  
Endogenous Metabolites

ABSTRACT Escherichia coli strains that are deficient in the Ada and Ogt DNA repair methyltransferases display an elevated spontaneous G:C-to-A:T transition mutation rate, and this increase has been attributed to mutagenic O 6-alkylguanine lesions being formed via the alkylation of DNA by endogenous metabolites. Here we test the frequently cited hypothesis thatS-adenosylmethionine (SAM) can act as a weak alkylating agent in vivo and that it contributes to endogenous DNA alkylation. By regulating the expression of the rat liver SAM synthetase and the bacteriophage T3 SAM hydrolase proteins in E. coli, a 100-fold range of SAM levels could be achieved. However, neither increasing nor decreasing SAM levels significantly affected spontaneous mutation rates, leading us to conclude that SAM is not a major contributor to the endogenous formation ofO 6-methylguanine lesions in E. coli.

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