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S-Adenosyl methionine

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https://www.readbyqxmd.com/read/28095853/crispri-mediated-metabolic-engineering-of-e-coli-for-o-methylated-anthocyanin-production
#1
Brady F Cress, Quentin D Leitz, Daniel C Kim, Teresita D Amore, Jon Y Suzuki, Robert J Linhardt, Mattheos A G Koffas
BACKGROUND: Anthocyanins are a class of brightly colored, glycosylated flavonoid pigments that imbue their flower and fruit host tissues with hues of predominantly red, orange, purple, and blue. Although all anthocyanins exhibit pH-responsive photochemical changes, distinct structural decorations on the core anthocyanin skeleton also cause dramatic color shifts, in addition to improved stabilities and unique pharmacological properties. In this work, we report for the first time the extension of the reconstituted plant anthocyanin pathway from (+)-catechin to O-methylated anthocyanins in a microbial production system, an effort which requires simultaneous co-option of the endogenous metabolites UDP-glucose and S-adenosyl-L-methionine (SAM or AdoMet)...
January 17, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28074264/nacl-stress-induces-cssams-gene-expression-in-cucumis-sativus-by-mediating-the-binding-of-csgt-3b-to-the-gt-1-element-within-the-cssams-promoter
#2
Li-Wei Wang, Mei-Wen He, Shi-Rong Guo, Min Zhong, Sheng Shu, Jin Sun
The CsSAMs promoter is a salt-stress-inducible promoter containing three GT-1 elements that are sufficient for the salt-stress response. The transcription factor CsGT-3b was found to bind to the GT-1 element. The S-adenosyl-L-methionine synthase (SAMs) gene is among the functional genes induced during environmental stress. However, little is known about the regulatory mechanism and upstream regulators of this salt-inducible gene in cucumber plants. Thus, it is necessary to understand the characteristics of the SAMs gene by analyzing its promoter and transcription factors...
January 10, 2017: Planta
https://www.readbyqxmd.com/read/28068060/structural-and-functional-basis-of-c-methylation-of-coumarin-scaffolds-by-novo
#3
Joanna C Sadler, Chun-Wa Chung, Julie E Mosley, Glenn A Burley, Luke D Humphreys
C-methylation of aromatic small molecules by C-methyltransferases (C-MTs) is an important biological trans-formation that involves C-C bond formation using S-adenosyl-L-methionine (SAM) as the methyl donor. Here, two advanc-es in the mechanistic understanding of C-methylation of the 8-position of coumarin substrates catalyzed by the C-MT No-vO from Streptomyces Spheroides are described. First, a crystal structure of NovO reveals the Arg116-Asn117 and His120-Arg121 motifs are essential for coumarin substrate binding...
January 9, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28054779/n6-adenosine-dna-methyltransferase-from-h-pylori-98-10-strain-in-complex-with-dna-and-adomet-structural-insights-from-in-silico-studies
#4
Swati Singh, Lalitha Guruprasad
Helicobacter pylori is a primitive Gram-negative bacterium that resides in the acidic environment of the human gastrointestinal tract, and some strains of this bacterium cause gastric ulcers and cancer. DNA methyltransferases (MTases) are promising drug targets for the treatment of cancer and other diseases that are also caused by epigenetic alternations of the genome. The N6-adenine-specific DNA MTase from H. pylori (M. Hpy N6mA) catalyzes the transfer of a methyl group from the cofactor S-adenosyl-l-methionine (AdoMet) to the flipped adenine of the substrate DNA...
January 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28045519/7-carboxy-7-deazaguanine-synthase-a-radical-s-adenosyl-l-methionine-enzyme-with-polar-tendencies
#5
Nathan A Bruender, Tsehai Aj Grell, Daniel P Dowling, Reid M McCarty, Catherine L Drennan, Vahe Bandarian
Radical S-adenosyl-L-methionine (SAM) enzymes are widely distributed and catalyze diverse reactions.  SAM binds to the unique iron atom of a site-differentiated [4Fe-4S] cluster and is reductively cleaved to generate a 5-deoxyadenosyl radical, which initiates turnover.  7-Carboxy-7-deazaguanine (CDG) synthase catalyzes a key step in the biosynthesis of 7-deazapurine containing natural products.  6-Carboxypterin (6-CP), an oxidized analog of the natural substrate 6-carboxy-5,6,7,8-tetrahydropterin (CPH4), is shown to be an alternate substrate for CDG synthase...
January 3, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28042932/novel-adomet-analogues-as-tools-for-enzymatic-transfer-of-photo-crosslinkers-and-capturing-rna-protein-interactions
#6
Fabian Muttach, Florain Mäsing, Armido Studer, Andrea Rentmeister
Elucidation of biomolecular interactions is of utmost importance in biochemistry. Photo-crosslinking offers the possibility to precisely determine RNA-protein interactions. However, despite the inherent specificity of enzymes, approaches for site-specific introduction of photo-crosslinking moieties into nucleic acids are scarce. Methyltransferases in combination with synthetic analogues of their natural cosubstrate S-adenosyl-L-methionine (AdoMet) allow for the post-synthetic site-specific modification of biomolecules...
January 2, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28031456/a-novel-motif-for-s-adenosyl-l-methionine-binding-by-the-ribosomal-rna-methyltransferase-tlya-from-mycobacterium-tuberculosis
#7
Marta A Witek, Emily G Kuiper, Elizabeth Minten, Emily K Crispell, Graeme L Conn
Capreomycin is a potent ribosome-targeting antibiotic that is an essential component of current antituberculosis treatments, particularly in the case of multi-drug resistant Mycobacterium tuberculosis (Mtb). Optimal capreomycin binding and Mtb ribosome inhibition requires ribosomal RNA (rRNA) methylation in both ribosome subunits by TlyA (Rv1694), an enzyme with dual 2'-O-methytransferase and putative hemolytic activities. Despite TlyA's important role in capreomycin sensitivity and identification of inactivating mutations in the corresponding Mtb gene tylA which cause resistance to capreomycin, our current structural and mechanistic understanding of TlyA action remains limited...
December 27, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28031370/binding-of-the-methyl-donor-sam-to-mers-cov-2-o-methyltransferase-nsp16-promotes-the-recruitment-of-the-allosteric-activator-nsp10
#8
Wahiba Aouadi, Alexandre Blanjoie, Jean-Jacques Vasseur, Françoise Debart, Bruno Canard, Etienne Decroly
: The Middle East respiratory syndrome coronavirus (MERS-CoV) non-structural protein 16 (nsp16) is an S-adenosyl-L-methionine (SAM)-dependent 2' -O-methyltransferase (MTase) that is thought to methylate the ribose 2' -OH of the first transcribed nucleotide (N1) of viral RNA cap structures. This 2' -O MTase activity is regulated by nsp10. The 2' -O methylation prevents virus detection by cell innate immunity mechanisms and viral translation inhibition by the interferon-stimulated IFIT-1 protein...
December 28, 2016: Journal of Virology
https://www.readbyqxmd.com/read/28027411/dna-repair-by-the-radical-sam-enzyme-spore-photoproduct-lyase-from-biochemistry-to-structural-investigations
#9
Olivier Berteau, Alhosna Benjdia
Radical S-adenosyl-L-methionine (SAM) enzymes have emerged as one of the last superfamilies of enzymes discovered to date. Arguably, it is the most versatile group of enzymes involved in at least 85 biochemical transformations. One of the founding members of this enzyme superfamily is the Spore Photoproduct (SP) lyase, a DNA repair enzyme catalyzing the direct reversal repair of a unique DNA lesion, the so-called spore photoproduct, back into two thymidine residues. Discovered more than 20 years ago in the bacterium Bacillus subtilis, SP lyase has been shown to be widespread in the endospore-forming Firmicutes from the Bacilli and Clostridia classes and to use radical-based chemistry to perform C-C bond breakage, a chemically challenging reaction...
December 27, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28004936/computational-study-of-the-degradation-of-s-adenosyl-methionine-in-water
#10
Timm Lankau, Tzu Nung Kuo, Chin Hui Yu
The degradation of S-adenosyl methionine (SAM) to homoserine-γ-lactone (HSL) and methyltioadenine (MTA) in water is studied with MD simulations. The AM1 Hamiltonian is used for the quantum part and the flexible AMBER force field for the H2O molecules. The MD simulations predict the free energy barrier for the degradation reaction to be between 109 and 112 kJ mol(-1) and an overall gain in free energy of -26 kJ mol(-1). The high barrier and the low energy gain of this reaction can be linked to interactions among the carboxylate group of the SAM molecule and solvent H2O molecules, which are not observed on the product side...
January 19, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28003820/feasibility-and-efficacy-of-s-adenosyl-l-methionine-in-patients-with-hbv-related-hcc-with-different-bclc-stages
#11
Tao Guo, Yukun He, Weijie Ma, Zhisu Liu, Quanyan Liu
Aims. To understand the feasibility and efficacy of treatment with SAMe in patients with hepatitis B-related HCC with different Barcelona Clinic Liver Cancer (BCLC) stages. Methods. We retrospectively enrolled 697 patients with BCLC early-stage (stages 0-A) and advanced-stage (stages B-C) HCC who underwent SAMe therapy (354 cases) or no SAMe therapy (343 cases). The baseline characteristics, postoperative recoveries, and 24-month overall survival rates of the patients in the 2 groups were compared. Cox regression model analysis was performed to confirm the independent variables influencing the survival rate...
2016: Gastroenterology Research and Practice
https://www.readbyqxmd.com/read/27998091/tryptophan-lyase-nosl-a-cornucopia-of-5-deoxyadenosyl-radical-mediated-transformations
#12
Dhananjay M Bhandari, Dmytro Fedoseyenko, Tadhg P Begley
Tryptophan lyase (NosL) is a radical S-adenosyl-l-methionine (SAM) enzyme that catalyzes the formation of 3-methyl-2-indolic acid from l-tryptophan. In this paper, we demonstrate that the 5'-deoxyadenosyl radical is considerably more versatile in its chemistry than previously anticipated: hydrogen atom abstraction from Nα-cyclopropyltryptophan occurs at Cα rather than the amino group with NosL Y90A and replacing the substrate amine with a ketone or an alkene changes the chemistry from hydrogen atom abstraction to double bond addition...
December 21, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27997431/attenuation-of-genome-wide-5-methylcytosine-level-is-an-epigenetic-feature-of-cutaneous-malignant-melanomas
#13
Goran Micevic, Nicholas Theodosakis, Janis M Taube, Marcus W Bosenberg, Nemanja Rodić
Epigenetic modification of DNA, namely covalent changes of cytosine residues, plays a key role in the maintenance of inactive chromatin regions, both in health and in disease. In the vast majority of malignant melanomas, the most notable known epigenetic abnormality is the attenuation of 5-hydroxymethylcytosine (5-hmC) residues. However, it remains unknown whether a decrease in 5-hmC represents a primary defect of melanoma cancer epigenome or whether it is secondary to the loss of 5-methylcytosine (5-mC), a chemical substrate for 5-hmC...
December 16, 2016: Melanoma Research
https://www.readbyqxmd.com/read/27997103/kinetic-isotope-effects-and-transition-state-structure-for-human-phenylethanolamine-n-methyltransferase
#14
Christopher F Stratton, Myles B Poulin, Quan Du, Vern L Schramm
Phenylethanolamine N-methyltransferase (PNMT) catalyzes the S-adenosyl-l-methionine (SAM)-dependent conversion of norepinephrine to epinephrine. Epinephrine has been associated with critical processes in humans including the control of respiration and blood pressure. Additionally, PNMT activity has been suggested to play a role in hypertension and Alzheimer's disease. In the current study, labeled SAM substrates were used to measure primary methyl-(14)C and (36)S and secondary methyl-(3)H, 5'-(3)H, and 5'-(14)C intrinsic kinetic isotope effects for human PNMT...
December 28, 2016: ACS Chemical Biology
https://www.readbyqxmd.com/read/27994052/bcid-is-a-radical-sam-enzyme-that-completes-bacteriochlorophyllide-e-biosynthesis-by-oxidizing-a-methyl-group-into-a-formyl-group-at-c-7
#15
Jennifer L Thweatt, Bryan H Ferlez, John H Golbeck, Donald A Bryant
Green bacteria are chlorophotorophs that synthesize bacteriochlorophyll (BChl) c, d, or e, which assemble into supramolecular, nanotubular structures in large light-harvesting structures called chlorosomes. The biosynthetic pathways of these chlorophylls are known except for one reaction. Null mutants of bciD, which encodes a putative radical-SAM protein, are unable to synthesize BChl e but accumulate BChl c; however, it is unknown whether BciD is sufficient to convert BChl c (or its precursor, bacteriochlorophyllide (BChlide) c into BChl e (or BChlide e)...
December 19, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27994001/stability-of-the-human-sperm-dna-methylome-to-folic-acid-fortification-and-short-term-supplementation
#16
D Chan, S McGraw, K Klein, L M Wallock, C Konermann, C Plass, P Chan, B Robaire, R A Jacob, C M T Greenwood, J M Trasler
STUDY QUESTION: Do short-term and long-term exposures to low-dose folic acid supplementation alter DNA methylation in sperm? SUMMARY ANSWER: No alterations in sperm DNA methylation patterns were found following the administration of low-dose folic acid supplements of 400 μg/day for 90 days (short-term exposure) or when pre-fortification of food with folic acid and post-fortification sperm samples (long-term exposure) were compared. WHAT IS KNOWN ALREADY: Excess dietary folate may be detrimental to health and DNA methylation profiles due to folate's role in one-carbon metabolism and the formation of S-adenosyl methionine, the universal methyl donor...
December 18, 2016: Human Reproduction
https://www.readbyqxmd.com/read/27989946/itraq-analysis-of-the-tobacco-leaf-proteome-reveals-that-rna-directed-dna-methylation-rddm-has-important-roles-in-defense-against-geminivirus-betasatellite-infection
#17
Xueting Zhong, Zhan Qi Wang, Ruyuan Xiao, Yaqin Wang, Yan Xie, Xueping Zhou
: Geminiviruses have caused serious losses in crop production. To investigate the mechanisms underlying host defenses against geminiviruses, an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomic approach was used to explore the expression profiles of proteins in Nicotiana benthamiana (N. benthamiana) leaves in response to tomato yellow leaf curl China virus (TYLCCNV) with its betasatellite (TYLCCNB) at an early phase. In total, 4155 proteins were identified and 272 proteins were changed differentially in response to TYLCCNV/TYLCCNB infection...
January 30, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/27986851/activation-mode-of-the-eukaryotic-m2g10-trna-methyltransferase-trm11-by-its-partner-protein-trm112
#18
Gabrielle Bourgeois, Julien Marcoux, Jean-Michel Saliou, Sarah Cianférani, Marc Graille
Post-transcriptional and post-translational modifications of factors involved in translation are very important for the control and accuracy of protein biosynthesis. Among these factors, tRNAs harbor the largest variety of grafted chemical structures, which participate in tRNA stability or mRNA decoding. Here, we focused on Trm112 protein, which associates with four different eukaryotic methyltransferases modifying tRNAs (Trm9 and Trm11) but also 18S-rRNA (Bud23) and translation termination factor eRF1 (Mtq2)...
December 15, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27986076/transcriptome-analysis-in-switchgrass-discloses-ecotype-difference-in-photosynthetic-efficiency
#19
Desalegn D Serba, Srinivasa Rao Uppalapati, Nick Krom, Shreyartha Mukherjee, Yuhong Tang, Kirankumar S Mysore, Malay C Saha
BACKGROUND: Switchgrass, a warm-season perennial grass studied as a potential dedicated biofuel feedstock, is classified into two main taxa - lowland and upland ecotypes - that differ in morphology and habitat of adaptation. But there is limited information on their inherent molecular variations. RESULTS: Transcriptome analysis by RNA-sequencing (RNA-Seq) was conducted for lowland and upland ecotypes to document their gene expression variations. Mapping of transcriptome to the reference genome (Panicum virgatum v1...
December 16, 2016: BMC Genomics
https://www.readbyqxmd.com/read/27981425/-1-h-15-n-13-c-backbone-resonance-assignments-of-human-soluble-catechol-o-methyltransferase-in-complex-with-s-adenosyl-l-methionine-and-3-5-dinitrocatechol
#20
Sylwia Czarnota, Nicola J Baxter, Matthew J Cliff, Jonathan P Waltho, Nigel S Scrutton, Sam Hay
Catechol O-methyltransferase (COMT) is an enzyme that plays a major role in catechol neurotransmitter deactivation. Inhibition of COMT can increase neurotransmitter levels, which provides a means of treatment for Parkinson's disease, schizophrenia and depression. COMT exists as two isozymes: a soluble cytoplasmic form (S-COMT), expressed in the liver and kidneys and a membrane-bound form (MB-COMT), found mostly in the brain. Here we report the backbone (1)H, (15)N and (13)C chemical shift assignments of S-COMT in complex with S-adenosyl-L-methionine, 3,5-dinitrocatechol and Mg(2+)...
December 15, 2016: Biomolecular NMR Assignments
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