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s-adenosyl-methionine

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https://www.readbyqxmd.com/read/28430424/elucidation-of-the-stereospecificity-of-c-methyltransferases-from-trans-at-polyketide-synthases
#1
Xinqiang Xie, Chaitan Khosla, David E Cane
S-Adenosyl methionine (SAM)-dependent C-methyltransferases are responsible for the C2-methylation of 3-ketoacyl-acyl carrier protein (ACP) intermediates to give the corresponding 2-methy-3-ketoacyl-ACP products during bacterial polyketide biosynthesis mediated by trans-AT polyketide synthases that lack integrated acyl transferase (AT) domains. A coupled ketoreductase (KR) assay was used to assign the stereochemistry of the C-methyltransferase-catalyzed reaction. Samples of chemoenzymatically-generated 3-ketopentanoyl-ACP (9) were incubated with SAM and BonMT2 from module 2 of the bongkrekic acid polyke-tide synthase...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28428565/small-methyltransferase-rlmh-assembles-a-composite-active-site-to-methylate-a-ribosomal-pseudouridine
#2
Cha San Koh, Rohini Madireddy, Timothy J Beane, Phillip D Zamore, Andrei A Korostelev
Eubacterial ribosomal large-subunit methyltransferase H (RlmH) methylates 23S ribosomal RNA pseudouridine 1915 (Ψ1915), which lies near the ribosomal decoding center. The smallest member of the SPOUT superfamily of methyltransferases, RlmH lacks the RNA recognition domain found in larger methyltransferases. The catalytic mechanism of RlmH enzyme is unknown. Here, we describe the structures of RlmH bound to S-adenosyl-methionine (SAM) and the methyltransferase inhibitor sinefungin. Our structural and biochemical studies reveal catalytically essential residues in the dimer-mediated asymmetrical active site...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28422052/folic-acid-reduces-tau-phosphorylation-by-regulating-pp2a-methylation-in-streptozotocin-induced-diabetic-mice
#3
Miaoyan Zheng, Chen Zou, Mengyue Li, Guowei Huang, Yuxia Gao, Huan Liu
High incidence rate of Alzheimer's disease (AD) is observed in patients with type 2 diabetes. Aggregated β-amyloid (Aβ) and hyperphosphorylated tau are the hallmarks of AD. Hyperphosphorylated tau has been detected in diabetic animals as well as in diabetic patients. Folates mediate the transfer of one carbon unit, required in various biochemical reactions. The effect of folate on tau phosphorylation in diabetic models still remains unknown. In this study, we investigated the effect and mechanism of folic acid on hyperphosphorylation of tau in streptozotocin (STZ)-induced diabetic mice...
April 19, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28369960/chronic-alcohol-exposure-differentially-alters-one-carbon-metabolism-in-rat-liver-and-brain
#4
James Auta, Huaibo Zhang, Subhash C Pandey, Alessandro Guidotti
BACKGROUND: Epigenetic mechanisms such as DNA methylation play an important role in regulating the pathophysiology of alcoholism. Chronic alcohol exposure leads to behavioral changes as well as decreased expression of genes associated with synaptic plasticity. In the liver, it has been documented that chronic alcohol exposure impairs methionine synthase (Ms) activity leading to a decrease in SAM/SAH ratio which results in DNA hypomethylation; however it is not known whether similar alterations of S-adenosyl methionine (SAM) and S-adenosyl homocysteine (SAH) levels are also produced in brain...
March 30, 2017: Alcoholism, Clinical and Experimental Research
https://www.readbyqxmd.com/read/28301141/reconstitution-and-substrate-specificity-of-the-radical-s-adenosyl-methionine-thiazole-c-methyltransferase-in-thiomuracin-biosynthesis
#5
Nilkamal Mahanta, Zhengan Zhang, Graham A Hudson, Wilfred A van der Donk, Douglas A Mitchell
Thiomuracin is a thiopeptide antibiotic with potent activity toward Gram-positive drug-resistant bacteria. Thiomuracin is biosynthesized from a precursor peptide, TbtA, by a complex array of posttranslational modifications. One of several intriguing transformations is the C-methylation of thiazole, occurring at an unactivated sp(2) carbon. Herein, we report the in vitro reconstitution of TbtI, the responsible radical S-adenosyl-methionine (rSAM) C-methyltransferase, which catalyzes the formation of 5-methylthiazole at a single site...
March 29, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28293840/assay-methods-for-acs-activity-and-acs-phosphorylation-by-map-kinases-in-vitro-and-in-vivo
#6
Xiaomin Han, Guojing Li, Shuqun Zhang
Ethylene, a gaseous phytohormone, has profound effects on plant growth, development, and adaptation to the environment. Ethylene-regulated processes begin with the induction of ethylene biosynthesis. There are two key steps in ethylene biosynthesis. The first is the biosynthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) from S-Adenosyl-Methionine (SAM), a common precursor in many metabolic pathways, which is catalyzed by ACC synthase (ACS). The second is the oxidative cleavage of ACC to form ethylene under the action of ACC oxidase (ACO)...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28259085/recent-advances-in-methyltransferase-biocatalysis
#7
REVIEW
Matthew R Bennett, Sarah A Shepherd, Victoria A Cronin, Jason Micklefield
S-adenosyl-L-methionine-dependent methyltransferses are ubiquitous in nature, methylating a vast range of small molecule metabolites, as well as biopolymers. This review covers the recent advances in the development of methyltransferase enzymes for synthetic applications, focusing on the methyltransferase catalyzed transformations with S-adenosyl methionine analogs, as well as non-native substrates. We discuss how metabolic engineering approaches have been used to enhance S-adenosyl methionine production in vivo...
March 2, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28255539/the-activity-of-a-yeast-family-16-methyltransferase-efm2-is-affected-by-a-conserved-tryptophan-and-its-n-terminal-region
#8
Joshua J Hamey, Gene Hart-Smith, Melissa A Erce, Marc R Wilkins
The Family 16 methyltransferases are a group of eukaryotic nonhistone protein methyltransferases. Sixteen of these have recently been described in yeast and human, but little is known about their sequence and structural features. Here we investigate one of these methyltransferases, Saccharomyces cerevisiae elongation factor methyltransferase 2 (Efm2), by site-directed mutagenesis and truncation. We show that an active site-associated tryptophan, invariant in Family 16 methyltransferases and at position 222 in Efm2, is important for methyltransferase activity...
December 2016: FEBS Open Bio
https://www.readbyqxmd.com/read/28237804/s-adenosyl-methionine-sam-attenuates-the-development-of-tolerance-to-analgesic-activity-of-morphine-in-rats
#9
Jatinder Katyal, Hemant Kumar, Dinesh Joshi, Yogendra Kumar Gupta
BACKGROUND: Development of tolerance to analgesic effect, on chronic administration of morphine, limits its clinical usefulness in pain management. S-adenosyl methionine (SAM) used for arthritis and approved as a supplement in many countries including United States was evaluated for reducing morphine tolerance. METHODS: Male 'Wistar' rats were used. The analgesic activity was determined using tail flick analgesiometer (Columbus Instruments, USA). Rats given morphine (7mg/kg), intraperitoneally (i...
February 22, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28237325/the-effect-of-lysophosphatidic-acid-together-with-interferon-tau-on-the-global-transcriptomic-profile-in-bovine-endometrial-cells
#10
Dorota Boruszewska, Ilona Kowalczyk-Zieba, Emilia Sinderewicz, Katarzyna Grycmacher, Joanna Staszkiewicz, Izabela Woclawek-Potocka
In cows, lysophosphatidic acid (LPA), which acts in an auto/paracrine manner, serves as a luteotropic factor during early pregnancy by stimulating progesterone and prostaglandin E2 secretion, thus protecting the bovine corpus luteum and early embryo development. Our hypothesis was that LPA exerted some local effects on the bovine endometrium prior to early embryo-maternal interactions and that interferon tau (IFNτ), the pregnancy recognition signal, modulated this action. In the present study, we applied an in vitro model involving whole-transcriptomic profiling to examine the effects of LPA on gene expression in bovine endometrial cells...
April 1, 2017: Theriogenology
https://www.readbyqxmd.com/read/28229434/preclinical-pharmacokinetics-and-pharmacodynamics-of-pinometostat-epz-5676-a-first-in-class-small-molecule-s-adenosyl-methionine-competitive-inhibitor-of-dot1l
#11
Nigel J Waters
Acute leukemias bearing mixed lineage leukemia (MLL) rearrangements are aggressive diseases characterized by a poor overall prognosis despite multi-agent chemotherapy. Aberrant fusion proteins involving the MLL histone methyltransferase (HMT) lead to recruitment of DOT1L, to a multi-protein complex resulting in aberrant methylation of histone H3 lysine 79 at MLL target genes, and ultimately enhanced expression of critical genes for hematopoietic differentiation, including HOXA9 and MEIS1, and as such defines the established mechanism for leukemogenesis in MLL-rearrangement (MLL-r) leukemias...
February 22, 2017: European Journal of Drug Metabolism and Pharmacokinetics
https://www.readbyqxmd.com/read/28225105/elucidating-the-biosynthetic-pathways-of-volatile-organic-compounds-in-mycobacterium-tuberculosis-through-a-computational-approach
#12
Purva Bhatter, Karthik Raman, Vani Janakiraman
Microbial volatile organic compounds (VOCs) have gained prominence in the recent past for their potential use as disease markers. The discovery of microbial VOCs has benefited 'difficult to detect' diseases such as tuberculosis (TB). Few of the identified VOCs of Mycobacterium tuberculosis (Mtb) are currently being explored for their diagnostic potential. However, very little is known about the biosynthesis of these small lipophilic molecules. Here, we propose putative biosynthetic pathways in Mycobacterium tuberculosis for three VOCs, namely methyl nicotinate, methyl phenylacetate and methyl p-anisate, using computational approaches...
February 22, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28224386/%C3%AE-bisabolol-inhibits-aspergillus-fumigatus-af239-growth-via-affecting-microsomal-%C3%A2-24-sterol-methyltransferase-as-a-crucial-enzyme-in-ergosterol-biosynthesis-pathway
#13
Zahra Jahanshiri, Masoomeh Shams-Ghahfarokhi, Farnoush Asghari-Paskiabi, Reza Saghiri, Mehdi Razzaghi-Abyaneh
Finding new compounds with antifungal properties is an important task due to the side effects of common antifungal drugs and emerging antifungal resistance in fungal strains. ∆(24)-sterol methyltransferase (24-SMT) is a crucial enzyme that plays important roles in fungal ergosterol biosynthesis pathway and is not found in humans. In the present study, the effects of α-bisabolol on Aspergillus fumigatus Af239 growth and ergosterol synthesis on the base of 24-SMT enzyme activity were studied; in addition, the expression of erg6, the gene encoded 24-SMT, was considered...
March 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28138060/rna-puzzles-round-iii-3d-rna-structure-prediction-of-five-riboswitches-and-one-ribozyme
#14
Zhichao Miao, Ryszard W Adamiak, Maciej Antczak, Robert T Batey, Alexander J Becka, Marcin Biesiada, Michał J Boniecki, Janusz M Bujnicki, Shi-Jie Chen, Clarence Yu Cheng, Fang-Chieh Chou, Adrian R Ferré-D'Amaré, Rhiju Das, Wayne K Dawson, Feng Ding, Nikolay V Dokholyan, Stanisław Dunin-Horkawicz, Caleb Geniesse, Kalli Kappel, Wipapat Kladwang, Andrey Krokhotin, Grzegorz E Łach, François Major, Thomas H Mann, Marcin Magnus, Katarzyna Pachulska-Wieczorek, Dinshaw J Patel, Joseph A Piccirilli, Mariusz Popenda, Katarzyna J Purzycka, Aiming Ren, Greggory M Rice, John Santalucia, Joanna Sarzynska, Marta Szachniuk, Arpit Tandon, Jeremiah J Trausch, Siqi Tian, Jian Wang, Kevin M Weeks, Benfeard Williams, Yi Xiao, Xiaojun Xu, Dong Zhang, Tomasz Zok, Eric Westhof
RNA-Puzzles is a collective experiment in blind 3D RNA structure prediction. We report here a third round of RNA-Puzzles. Five puzzles, 4, 8, 12, 13, 14, all structures of riboswitch aptamers and puzzle 7, a ribozyme structure, are included in this round of the experiment. The riboswitch structures include biological binding sites for small molecules (S-adenosyl methionine, cyclic diadenosine monophosphate, 5-amino 4-imidazole carboxamide riboside 5'-triphosphate, glutamine) and proteins (YbxF), and one set describes large conformational changes between ligand-free and ligand-bound states...
May 2017: RNA
https://www.readbyqxmd.com/read/28135835/clinical-use-of-nutraceuticals-in-the-adjunctive-treatment-of-depression-in-mood-disorders
#15
Jerome Sarris
OBJECTIVES: The aim of this paper is to detail a summary of the current evidence in this area, to better inform clinical practice. Our recent systematic reviews and meta-analyses of nutrient pharmacotherapies in the treatment unipolar depression revealed primarily positive results for replicated studies testing S-adenosyl methionine (SAMe), methylfolate, omega-3 (EPA or ethyl-EPA), and Vitamin D; with supportive isolated studies found for creatine and an amino acid combination. Mixed results were found for zinc, folic acid, Vitamin C, and tryptophan; and non-significant study results for inositol...
January 1, 2017: Australasian Psychiatry: Bulletin of Royal Australian and New Zealand College of Psychiatrists
https://www.readbyqxmd.com/read/28004936/computational-study-of-the-degradation-of-s-adenosyl-methionine-in-water
#16
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/27997431/attenuation-of-genome-wide-5-methylcytosine-level-is-an-epigenetic-feature-of-cutaneous-malignant-melanomas
#17
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/27994001/stability-of-the-human-sperm-dna-methylome-to-folic-acid-fortification-and-short-term-supplementation
#18
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...
February 2017: Human Reproduction
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/27958669/an-orthogonal-d2-o-based-induction-system-that-provides-insights-into-d-amino-acid-pattern-formation-by-radical-s-adenosylmethionine-peptide-epimerases
#20
Brandon I Morinaka, Marjan Verest, Michael F Freeman, Muriel Gugger, Jörn Piel
Radical S-adenosyl methionine peptide epimerases (RSPEs) are an enzyme family that accomplishes regiospecific and irreversible introduction of multiple d-configured residues into ribosomally encoded peptides. Collectively, RSPEs can generate diverse epimerization patterns in a wide range of substrates. Previously, the lack of rapid methods to localize epimerized residues has impeded efforts to investigate the function and applicative potential of RSPEs. An efficient mass spectrometry-based assay is introduced that permits characterization of products generated in E...
December 13, 2016: Angewandte Chemie
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