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https://www.readbyqxmd.com/read/28640310/spectroscopic-evidence-for-cofactor-substrate-interaction-in-the-radical-sam-enzyme-tyw1
#1
Velavan Kathirvelu, Phanélie Perche-Letuvée, Jean-Marc Latour, Mohamed Atta, Farhad Forouhar, Serge Gambarelli, Ricardo Garcia-Serres
TYW1 is a metalloenzyme involved in the modifications of guanosine 37 of Phe-tRNA of Eukaryota and Archaea. It catalyzes the second step of Wybutosine biosynthesis, which consists of the formation of the tricyclic compound imG-14 from m(1)G using pyruvate and SAM (S-adenosyl-methionine) as co-substrates. Two [4Fe-4S] clusters are needed in the catalytic process. One effects the reductive binding of SAM, which initiates the radical reaction that inserts a C-C moiety into m(1)G. The other [4Fe-4S] cluster binds the pyruvate molecule that provides the C-C motif...
June 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28615450/cellular-requirements-for-iron-sulfur-cluster-insertion-into-the-antiviral-radical-sam-protein-viperin
#2
Arunkumar S Upadhyay, Oliver Stehling, Christakis Panayiotou, Ralf Rösser, Roland Lill, Anna K Överby
Viperin (RSAD2) is an interferon-stimulated antiviral protein that belongs to the radical S-adenosyl methionine (SAM) enzyme family. Viperin's iron-sulfur (Fe/S) cluster is critical for its antiviral activity against many different viruses. CIA1 (CIAO1), an essential component of the cytosolic iron-sulfur protein assembly (CIA) machinery, is crucial for Fe/S cluster insertion into viperin and hence for viperin's antiviral activity. In the CIA pathway, CIA1 cooperates with CIA2A, CIA2B, and MMS19 targeting factors to form various complexes that mediate the dedicated maturation of specific Fe/S recipient proteins...
June 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28601431/serine-and-functional-metabolites-in-cancer
#3
REVIEW
Alice C Newman, Oliver D K Maddocks
Folate metabolism functions to supply one-carbon units that are vital for a range of biochemical reactions. Cancer cells can utilise serine as a major source of one-carbon units, rendering them dependent upon extracellular serine uptake or de novo serine synthesis for maximal growth and proliferation. One-carbon units are required for the production of critical cellular components, such as nucleotides, which enable cancer cells to maintain high proliferate rates. Of recent interest, one-carbon metabolism contributes to the biosynthesis and recycling of functional metabolites, such as ATP, S-adenosyl-methionine (SAM), and NAD(P)H, with important downstream consequences for cancer cell survival...
June 7, 2017: Trends in Cell Biology
https://www.readbyqxmd.com/read/28601227/trmd-a-methyl-transferase-for-trna-methylation-with-m-1-g37
#4
Ya-Ming Hou, Ryuma Matsubara, Ryuichi Takase, Isao Masuda, Joanna I Sulkowska
TrmD is an S-adenosyl methionine (AdoMet)-dependent methyl transferase that synthesizes the methylated m(1)G37 in tRNA. TrmD is specific to and essential for bacterial growth, and it is fundamentally distinct from its eukaryotic and archaeal counterpart Trm5. TrmD is unusual by using a topological protein knot to bind AdoMet. Despite its restricted mobility, the TrmD knot has complex dynamics necessary to transmit the signal of AdoMet binding to promote tRNA binding and methyl transfer. Mutations in the TrmD knot block this intramolecular signaling and decrease the synthesis of m(1)G37-tRNA, prompting ribosomes to +1-frameshifts and premature termination of protein synthesis...
2017: Enzymes
https://www.readbyqxmd.com/read/28576826/archaeal-fibrillarin-nop5-heterodimer-2-o-methylates-rna-independently-of-the-c-d-guide-rnp-particle
#5
Miglė Tomkuvienė, Janina Ličytė, Ingrida Olendraitė, Zita Liutkevičiūtė, Béatrice Clouet-d'Orval, Saulius Klimašauskas
Archaeal fibrillarin (aFib) is a well-characterized S-Adenosyl methionine (SAM)-dependent RNA 2'-O-methyltransferase that is known to act in a large C/D ribonucleoprotein (RNP) complex together with Nop5 and L7Ae proteins and a box C/D guide RNA. In the reaction, the guide RNA is critical to direct the methylation reaction to a specific site in tRNA or rRNA by sequence complementarity. Here we show that Pyrococcus abyssi aFib-Nop5 heterodimer can alone perform a SAM-dependent 2'-O-methylation of 16S and 23S ribosomal RNAs in vitro independently of L7Ae and C/D guide RNAs...
June 2, 2017: RNA
https://www.readbyqxmd.com/read/28556625/suppression-of-a-methionine-synthase-by-calmodulin-under-environmental-stress-in-the-entomopathogenic-fungus-beauveria-bassiana
#6
Jiyoung Kim, Junsang Oh, Deok-Hyo Yoon, Gi-Ho Sung
Methionine synthase (MetE, EC 2.1.1.14) catalyzes the final step in the methionine biosynthetic pathway. Methionine biosynthesis plays a major role in protein biogenesis and is the source of S-adenosyl methionine (SAM), the universal donor of methyl groups. In this study, we demonstrated that BbMetE acts as a typical MetE enzyme in the entomopathogenic fungus Beauveria bassiana. In addition, we found that BbMetE binds to calmodulin (CaM) in vitro and in vivo. The functional role of CaM binding to BbMetE was to negatively regulate BbMetE activity in B...
May 29, 2017: Environmental Microbiology Reports
https://www.readbyqxmd.com/read/28552342/interplay-between-mitochondrial-metabolism-and-oxidative-stress-in-ischemic-stroke-an-epigenetic-connection
#7
REVIEW
Parimala Narne, Vimal Pandey, Prakash Babu Phanithi
The advent of epigenetics brought in a tectonic shift in the understanding of molecular basis of complex diseases like ischemic stroke (IS). Substantial scientific inquiry into the epigenetic basis of neurodegenerative diseases has bolstered the idea that altered carbon flux into central carbon metabolism and disturbed redox states govern the attendant transcriptional profiles through stochastic epigenetic changes. In view of an increasing understanding of the link between mitochondrial energy metabolism, oxidative stress and epigenetics in IS, the hitherto underappreciated 'neuroenergetics' is gaining sustained attention...
May 24, 2017: Molecular and Cellular Neurosciences
https://www.readbyqxmd.com/read/28535932/charting-novel-allergens-from-date-palm-pollen-phoenix-sylvestris-using-homology-driven-proteomics
#8
Bodhisattwa Saha, Naren Pandey, Swati Gupta Bhattacharya
Pollen grains from Phoenix sylvestris (date palm), a commonly cultivated tree in India has been found to cause severe allergic diseases in an increasing percentage of hypersensitive individuals. To unearth its allergenic components, pollen protein were profiled by two-dimensional gel electrophoresis followed by immunoblotting with date palm pollen sensitive patient sera. Allergens were identified by MALDI-TOF/TOF employing a layered proteomic approach combining conventional database dependent search and manual de novo sequencing followed by homology-based search as Phoenix sylvestris is unsequenced...
May 20, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/28515364/nicotinamide-metabolism-regulates-glioblastoma-stem-cell-maintenance
#9
Jinkyu Jung, Leo J Y Kim, Xiuxing Wang, Qiulian Wu, Tanwarat Sanvoranart, Christopher G Hubert, Briana C Prager, Lisa C Wallace, Xun Jin, Stephen C Mack, Jeremy N Rich
Metabolic dysregulation promotes cancer growth through not only energy production, but also epigenetic reprogramming. Here, we report that a critical node in methyl donor metabolism, nicotinamide N-methyltransferase (NNMT), ranked among the most consistently overexpressed metabolism genes in glioblastoma relative to normal brain. NNMT was preferentially expressed by mesenchymal glioblastoma stem cells (GSCs). NNMT depletes S-adenosyl methionine (SAM), a methyl donor generated from methionine. GSCs contained lower levels of methionine, SAM, and nicotinamide, but they contained higher levels of oxidized nicotinamide adenine dinucleotide (NAD+) than differentiated tumor cells...
May 18, 2017: JCI Insight
https://www.readbyqxmd.com/read/28430424/elucidation-of-the-stereospecificity-of-c-methyltransferases-from-trans-at-polyketide-synthases
#10
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 polyketide synthase...
May 3, 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
#11
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
#12
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
#13
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 S-adenosyl methionine/S-adenosyl homocysteine (SAM/SAH) ratio which results in DNA hypomethylation; however, it is not known whether similar alterations of SAM and SAH levels are also produced in brain...
June 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
#14
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
#15
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
#16
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...
April 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
#17
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
#18
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
#19
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
#20
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
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