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https://www.readbyqxmd.com/read/28643349/a-qm-mm-study-of-the-catalytic-mechanism-of-sam-methyltransferase-rlmn-from-escherichia-coli
#1
Chenxiao Zhao, Lihua Dong, Yongjun Liu
RlmN is a radical S-adenosylmethionine (SAM) enzyme that catalyzes the C2 methylation of adenosine 2503 (A2503) in 23S rRNA and adenosine 37 (A37) in several Escherichia coli transfer RNAs (tRNA). The catalytic reaction of RlmN is distinctly different from that of typical SAM-dependent methyltransferases that employs an SN 2 mechanism, but follows a ping-pong mechanism which involves the intermediate methylation of a conserved cysteine residue. Recently, the x-ray structure of a key intermediate in the RlmN reaction has been reported, allowing us to perform combined quantum mechanics and molecular mechanics (QM/MM) calculations to delineate the reaction details of RlmN at atomic level...
June 23, 2017: Proteins
https://www.readbyqxmd.com/read/28607080/structural-studies-of-viperin-an-antiviral-radical-sam-enzyme
#2
Michael K Fenwick, Yue Li, Peter Cresswell, Yorgo Modis, Steven E Ealick
Viperin is an IFN-inducible radical S-adenosylmethionine (SAM) enzyme that inhibits viral replication. We determined crystal structures of an anaerobically prepared fragment of mouse viperin (residues 45-362) complexed with S-adenosylhomocysteine (SAH) or 5'-deoxyadenosine (5'-dAdo) and l-methionine (l-Met). Viperin contains a partial (βα)6-barrel fold with a disordered N-terminal extension (residues 45-74) and a partially ordered C-terminal extension (residues 285-362) that bridges the partial barrel to form an overall closed barrel structure...
June 12, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28601227/trmd-a-methyl-transferase-for-trna-methylation-with-m-1-g37
#3
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/28593035/smchd1-regulates-a-limited-set-of-gene-clusters-on-autosomal-chromosomes
#4
Amanda G Mason, Roderick C Slieker, Judit Balog, Richard J L F Lemmers, Chao-Jen Wong, Zizhen Yao, Jong-Won Lim, Galina N Filippova, Enrico Ne, Rabi Tawil, Bas T Heijmans, Stephen J Tapscott, Silvère M van der Maarel
BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is in most cases caused by a contraction of the D4Z4 macrosatellite repeat on chromosome 4 (FSHD1) or by mutations in the SMCHD1 or DNMT3B gene (FSHD2). Both situations result in the incomplete epigenetic repression of the D4Z4-encoded retrogene DUX4 in somatic cells, leading to the aberrant expression of DUX4 in the skeletal muscle. In mice, Smchd1 regulates chromatin repression at different loci, having a role in CpG methylation establishment and/or maintenance...
2017: Skeletal Muscle
https://www.readbyqxmd.com/read/28587678/smchd1-regulates-a-limited-set-of-gene-clusters-on-autosomal-chromosomes
#5
Amanda G Mason, Roderick C Slieker, Judit Balog, Richard J L F Lemmers, Chao-Jen Wong, Zizhen Yao, Jong-Won Lim, Galina N Filippova, Enrico Ne, Rabi Tawil, Bas T Heijmans, Stephen J Tapscott, Silvère M van der Maarel
BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is in most cases caused by a contraction of the D4Z4 macrosatellite repeat on chromosome 4 (FSHD1) or by mutations in the SMCHD1 or DNMT3B gene (FSHD2). Both situations result in the incomplete epigenetic repression of the D4Z4-encoded retrogene DUX4 in somatic cells, leading to the aberrant expression of DUX4 in the skeletal muscle. In mice, Smchd1 regulates chromatin repression at different loci, having a role in CpG methylation establishment and/or maintenance...
June 6, 2017: Skeletal Muscle
https://www.readbyqxmd.com/read/28576863/evolving-mistranslating-trnas-through-a-phenotypically-ambivalent-intermediate-in-saccharomyces-cerevisiae
#6
Matthew D Berg, Kyle S Hoffman, Julie Genereaux, Safee Mian, Ryan S Trussler, David B Haniford, Patrick O'Donoghue, Christopher J Brandl
The genetic code converts information from nucleic acid into protein. The genetic code was thought to be immutable, yet many examples in nature indicate that variations to the code provide a selective advantage. We used a sensitive selection system involving suppression of a deleterious allele (tti2-L187P) in Saccharomyces cerevisiae to detect mistranslation and identify mechanisms that allow genetic code evolution. Though tRNA(Ser) containing a proline anticodon (UGG) is toxic, using our selection system, we identified four tRNA(Ser)UGG variants, each with a single mutation, that mistranslate at a tolerable level...
June 2, 2017: Genetics
https://www.readbyqxmd.com/read/28576826/archaeal-fibrillarin-nop5-heterodimer-2-o-methylates-rna-independently-of-the-c-d-guide-rnp-particle
#7
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/28575027/linking-epigenetic-function-to-electrostatics-the-dnmt2-structural-model-example
#8
Gilberto Cavalheiro Vieira, Gustavo Fioravanti Vieira, Marialva Sinigaglia, Vera Lúcia da Silva Valente
The amino acid sequence of DNMT2 is very similar to the catalytic domains of bacterial and eukaryotic proteins. However, there is great variability in the region of recognition of the target sequence. While bacterial DNMT2 acts as a DNA methyltransferase, previous studies have indicated low DNA methylation activity in eukaryotic DNMT2, with preference by tRNA methylation. Drosophilids are known as DNMT2-only species and the DNA methylation phenomenon is a not elucidated case yet, as well as the ontogenetic and physiologic importance of DNMT2 for this species group...
2017: PloS One
https://www.readbyqxmd.com/read/28567122/a-functional-role-for-the-monomethylated-gln-51-and-lys-53-residues-of-the-49ggqtk53-motif-of-el42-from-human-80s-ribosomes
#9
Stéphanie Eustache, Jean-Bernard Créchet, Tahar Bouceba, Jun-Ichi Nakayama, Mayo Tanaka, Mieko Suzuki, Anne Woisard, Pierre Tuffery, Soria Baouz, Codjo Hountondji
BACKGROUND: We have previously demonstrated that the eukaryote-specific ribosomal protein eL42 of the human 80S ribosome contains seven monomethylated residues, among which are the Gln-51 and Lys-53 residues contained in the 47GFGGQTK53 sequence conserved in all eukaryotic 80S ribosomes. This sequence contains the methylated and universally conserved GGQ motif common for all class-1 translation termination factors responsible for stop codon recognition and for triggering the hydrolysis of the P site-bound peptidyl-tRNA...
2017: Open Biochemistry Journal
https://www.readbyqxmd.com/read/28544464/structural-and-biochemical-insights-into-the-2-o-methylation-of-pyrimidines-34-in-trna
#10
Panjiao Pang, Xiangyu Deng, Zhong Wang, Wei Xie
tRNA molecules undergo extensive modifications during their maturation process and these modifications play important cellular roles. TrmL is a tRNA-modification enzyme that catalyzes the transfer of a methyl group to the 2' hydroxyl group of the pyrimidines at the wobble position 34 in two tRNA(L)(eu) isoacceptors, but the mechanism remains elusive. In this study, we determined the crystal structure of TrmL from Thermus Thermophilus (TtTrmL) to 1.7 Å. The enzyme contains only the conserved minimal SPOUT fold, but displays distinct biochemical behaviors from its Escherichia coli counterpart EcTrmL...
May 25, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28531330/structural-basis-for-substrate-binding-and-catalytic-mechanism-of-a-human-rna-m5c-methyltransferase-nsun6
#11
Ru-Juan Liu, Tao Long, Jing Li, Hao Li, En-Duo Wang
5-methylcytosine (m5C) modifications of RNA are ubiquitous in nature and play important roles in many biological processes such as protein translational regulation, RNA processing and stress response. Aberrant expressions of RNA:m5C methyltransferases are closely associated with various human diseases including cancers. However, no structural information for RNA-bound RNA:m5C methyltransferase was available until now, hindering elucidation of the catalytic mechanism behind RNA:m5C methylation. Here, we have solved the structures of NSun6, a human tRNA:m5C methyltransferase, in the apo form and in complex with a full-length tRNA substrate...
May 22, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28506829/an-asymmetric-dimeric-structure-of-trmj-trna-methyltransferase-from-zymomonas-mobilis-with-a-flexible-c-terminal-dimer
#12
Do-Heon Gu, Mi-Young Park, Jeong-Sun Kim
The tRNA methyltransferase J (TrmJ) and D (TrmD) catalyze the transferring reaction of a methyl group to the tRNA anticodon loop. They commonly have the N-terminal domain (NTD) and the C-terminal domain (CTD). Whereas two monomeric CTDs symmetrically interact with a dimeric NTD in TrmD, a CTD dimer has exhibited an asymmetric interaction with the NTD dimer in the presence of a product. The elucidated apo-structure of the full-length TrmJ from Zymomonas mobilis ZM4 shows a dimeric CTD that asymmetrically interacts with the NTD dimer, thereby distributing non-symmetrical potential charge on the both side of the protein surface...
May 12, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28488916/observing-the-fate-of-trna-and-its-modifications-by-nucleic-acid-isotope-labeling-mass-spectrometry-nail-ms
#13
Matthias Heiss, Valentin F Reichle, Stefanie Kellner
RNA in yeast, especially rRNA and tRNA are heavily modified to fulfill their function in protein translation. Using biosynthetic stable isotope labeled internal standards we quantified 12 modified nucleosides in tRNA from S. cerevisiae over 24 hours. We observed different quantities of modified nucleosides in dependence of the growth phase. To elucidate the underlying mechanism of the observed tRNA modification profile adaptation, it is necessary to distinguish the pre-existing tRNA pool and its modifications from newly-synthesized tRNAs...
May 10, 2017: RNA Biology
https://www.readbyqxmd.com/read/28476776/cytosine-methylation-by-dnmt2-facilitates-stability-and-survival-of-hiv-1-rna-in-the-host-cell-during-infection
#14
Rachana Roshan Dev, Rakesh Ganji, Satya Prakash Singh, Sundarasamy Mahalingam, Sharmistha Banerjee, Sanjeev Khosla
The enigmatic methyltransferase, DNMT2 (DNA methyltransferase 2), structurally resembles a DNA methyltransferase, but has been shown to be a tRNA methyltransferase targeting cytosine within a specific CpG in different tRNA molecules. We had previously shown that, during environmental stress conditions, DNMT2 is re-localized from the nucleus to the cytoplasmic stress granules (SGs) and is associated with RNA-processing proteins. In the present study, we show that DNMT2 binds and methylates various mRNA species in a sequence-independent manner and gets re-localized to SGs in a phosphorylation-dependent manner...
June 6, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28418649/nature-s-selection-of-geranyl-group-as-a-trna-modification-the-effects-of-chain-length-on-base-pairing-specificity
#15
Phensinee Haruehanroengra, Sweta Vangaveti, Srivathsan V Ranganathan, Rui Wang, Alan Chen, Jia Sheng
The recently discovered geranyl modification on the 2-thio position of wobble U34 residues in tRNA(Glu), tRNA(Lys), and tRNA(Gln) in several bacteria has been found to enhance the U:G pairing specificity and reduce the frameshifting error during translation. It is a fundamentally interesting question why nature chose a C10 terpene group in tRNA systems. In this study, we explore the significance of the terpene length on base-paring stability and specificity using a series of 2-thiouridine analogues containing different lengths of carbon chains, namely, methyl- (C1), dimethylallyl- (C5), and farnesyl-modified (C15) 2-thiothymidines in a DNA duplex...
April 18, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28371071/selective-enzymatic-demethylation-of-n-2-n-2-dimethylguanosine-in-rna-and-its-application-in-high-throughput-trna-sequencing
#16
Qing Dai, Guanqun Zheng, Michael H Schwartz, Wesley C Clark, Tao Pan
The abundant Watson-Crick face methylations in biological RNAs such as N(1) -methyladenosine (m(1) A), N(1) -methylguanosine (m(1) G), N(3) -methylcytosine (m(3) C), and N(2) ,N(2) -dimethylguanosine (m(2)2 G) cause significant obstacles for high-throughput RNA sequencing by impairing cDNA synthesis. One strategy to overcome this obstacle is to remove the methyl group on these modified bases prior to cDNA synthesis using enzymes. The wild-type E. coli AlkB and its D135S mutant can remove most of m(1) A, m(1) G, m(3) C modifications in transfer RNA (tRNA), but they work poorly on m(2)2 G...
April 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28357324/sulfur-transfer-and-activation-by-ubiquitin-like-modifier-system-uba4%C3%A2-urm1-link-protein-urmylation-and-trna-thiolation-in-yeast
#17
André Jüdes, Alexander Bruch, Roland Klassen, Mark Helm, Raffael Schaffrath
Urm1 is a unique dual-function member of the ubiquitin protein family and conserved from yeast to man. It acts both as a protein modifier in ubiquitin-like urmylation and as a sulfur donor for tRNA thiolation, which in concert with the Elongator pathway forms 5-methoxy-carbonyl-methyl-2-thio (mcm(5)s(2)) modified wobble uridines (U34) in anticodons. Using Saccharomyces cerevisiae as a model to study a relationship between these two functions, we examined whether cultivation temperature and sulfur supply previously implicated in the tRNA thiolation branch of the URM1 pathway also contribute to proper urmylation...
October 24, 2016: Microbial Cell
https://www.readbyqxmd.com/read/28349464/high-throughput-small-rna-sequencing-enhanced-by-alkb-facilitated-rna-de-methylation-arm-seq
#18
Eva Hrabeta-Robinson, Erin Marcus, Aaron E Cozen, Eric M Phizicky, Todd M Lowe
N (1)-methyladenosine (m(1)A), N (3)-methylcytidine (m(3)C), and N (1)-methylguanosine (m(1)G) are common in transfer RNA (tRNA) and tRNA-derived fragments. These modifications alter Watson-Crick base-pairing, and cause pauses or stops during reverse transcription required for most high-throughput RNA sequencing protocols, resulting in inefficient detection of methyl-modified RNAs. Here, we describe a procedure to demethylate RNAs containing m(1)A, m(3)C, or m(1)G using the Escherichia coli dealkylating enzyme AlkB, along with instructions for subsequent processing with widely used protocols for small RNA sequencing...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28349451/comparative-analysis-of-ribonucleic-acid-digests-card-by-mass-spectrometry
#19
Mellie June Paulines, Patrick A Limbach
We describe the comparative analysis of ribonucleic acid digests (CARD) approach for RNA modification analysis. This approach employs isotope labeling during RNase digestion, which allows the direct comparison of a tRNA of unknown modification status against a reference tRNA, whose sequence or modification status is known. The reference sample is labeled with (18)O during RNase digestion while the candidate (unknown) sample is labeled with (16)O. These RNase digestion products are combined and analyzed by mass spectrometry...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28335556/trm5-and-trmd-two-enzymes-from-distinct-origins-catalyze-the-identical-trna-modification-m%C3%A2-g37
#20
REVIEW
Sakurako Goto-Ito, Takuhiro Ito, Shigeyuki Yokoyama
The N¹-atom of guanosine at position 37 in transfer RNA (tRNA) is methylated by tRNA methyltransferase 5 (Trm5) in eukaryotes and archaea, and by tRNA methyltransferase D (TrmD) in bacteria. The resultant modified nucleotide m¹G37 positively regulates the aminoacylation of the tRNA, and simultaneously functions to prevent the +1 frameshift on the ribosome. Interestingly, Trm5 and TrmD have completely distinct origins, and therefore bear different tertiary folds. In this review, we describe the different strategies utilized by Trm5 and TrmD to recognize their substrate tRNAs, mainly based on their crystal structures complexed with substrate tRNAs...
March 21, 2017: Biomolecules
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