Base de dados : MEDLINE
Pesquisa : D03.633.100.759.590.454.500 [Categoria DeCS]
Referências encontradas : 96 [refinar]
Mostrando: 1 .. 10   no formato [Detalhado]

página 1 de 10 ir para página                        

  1 / 96 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28208632
[Au] Autor:Ehrenhofer-Murray AE
[Ad] Endereço:Institut für Biologie, Humboldt-Universität zu Berlin, 10099 Berlin, Germany. ann.ehrenhofer-murray@hu-berlin.de.
[Ti] Título:Cross-Talk between Dnmt2-Dependent tRNA Methylation and Queuosine Modification.
[So] Source:Biomolecules;7(1), 2017 Feb 10.
[Is] ISSN:2218-273X
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:Enzymes of the Dnmt2 family of methyltransferases have yielded a number of unexpected discoveries. The first surprise came more than ten years ago when it was realized that, rather than being DNA methyltransferases, Dnmt2 enzymes actually are transfer RNA (tRNA) methyltransferases for cytosine-5 methylation, foremost C38 (m5C38) of tRNAAsp. The second unanticipated finding was our recent discovery of a nutritional regulation of Dnmt2 in the fission yeast Schizosaccharomyces pombe. Significantly, the presence of the nucleotide queuosine in tRNAAsp strongly stimulates Dnmt2 activity both in vivo and in vitro in S. pombe. Queuine, the respective base, is a hypermodified guanine analog that is synthesized from guanosine-5'-triphosphate (GTP) by bacteria. Interestingly, most eukaryotes have queuosine in their tRNA. However, they cannot synthesize it themselves, but rather salvage it from food or from gut microbes. The queuine obtained from these sources comes from the breakdown of tRNAs, where the queuine ultimately was synthesized by bacteria. Queuine thus has been termed a micronutrient. This review summarizes the current knowledge of Dnmt2 methylation and queuosine modification with respect to translation as well as the organismal consequences of the absence of these modifications. Models for the functional cooperation between these modifications and its wider implications are discussed.
[Mh] Termos MeSH primário: DNA (Citosina-5-)-Metiltransferases/metabolismo
Nucleosídeo Q/química
RNA de Transferência/química
[Mh] Termos MeSH secundário: Animais
Bactérias/genética
Bactérias/metabolismo
Regulação Fúngica da Expressão Gênica
Seres Humanos
Metilação
Nucleosídeo Q/metabolismo
Schizosaccharomyces/genética
Schizosaccharomyces/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
57072-36-3 (Nucleoside Q); 9014-25-9 (RNA, Transfer); EC 2.1.1.37 (DNA (Cytosine-5-)-Methyltransferases)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170218
[St] Status:MEDLINE


  2 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28128549
[Au] Autor:Zallot R; Ross R; Chen WH; Bruner SD; Limbach PA; de Crécy-Lagard V
[Ad] Endereço:Department of Microbiology and Cell Science, University of Florida , Gainesville, Florida 32611, United States.
[Ti] Título:Identification of a Novel Epoxyqueuosine Reductase Family by Comparative Genomics.
[So] Source:ACS Chem Biol;12(3):844-851, 2017 Mar 17.
[Is] ISSN:1554-8937
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The reduction of epoxyqueuosine (oQ) is the last step in the synthesis of the tRNA modification queuosine (Q). While the epoxyqueuosine reductase (EC 1.17.99.6) enzymatic activity was first described 30 years ago, the encoding gene queG was only identified in Escherichia coli in 2011. Interestingly, queG is absent from a large number of sequenced genomes that harbor Q synthesis or salvage genes, suggesting the existence of an alternative epoxyqueuosine reductase in these organisms. By analyzing phylogenetic distributions, physical gene clustering, and fusions, members of the Domain of Unknown Function 208 (DUF208) family were predicted to encode for an alternative epoxyqueuosine reductase. This prediction was validated with genetic methods. The Q modification is present in Lactobacillus salivarius, an organism missing queG but harboring the duf208 gene. Acinetobacter baylyi ADP1 is one of the few organisms that harbor both QueG and DUF208, and deletion of both corresponding genes was required to observe the absence of Q and the accumulation of oQ in tRNA. Finally, the conversion oQ to Q was restored in an E. coli queG mutant by complementation with plasmids harboring duf208 genes from different bacteria. Members of the DUF208 family are not homologous to QueG enzymes, and thus, duf208 is a non-orthologous replacement of queG. We propose to name DUF208 encoding genes as queH. While QueH contains conserved cysteines that could be involved in the coordination of a Fe/S center in a similar fashion to what has been identified in QueG, no cobalamin was identified associated with recombinant QueH protein.
[Mh] Termos MeSH primário: Genômica
Nucleosídeo Q/análogos & derivados
Oxirredutases/metabolismo
[Mh] Termos MeSH secundário: Lactobacillus/enzimologia
Lactobacillus/genética
Nucleosídeo Q/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
107865-20-3 (nucleoside oQ); 57072-36-3 (Nucleoside Q); EC 1.- (Oxidoreductases)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170714
[Lr] Data última revisão:
170714
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170128
[St] Status:MEDLINE
[do] DOI:10.1021/acschembio.6b01100


  3 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28069821
[Au] Autor:Van Vlack ER; Topp S; Seeliger JC
[Ad] Endereço:Department of Chemistry, Stony Brook University, Stony Brook, New York, USA.
[Ti] Título:Characterization of Engineered PreQ1 Riboswitches for Inducible Gene Regulation in Mycobacteria.
[So] Source:J Bacteriol;199(6), 2017 Mar 15.
[Is] ISSN:1098-5530
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:We report here the behavior of naturally occurring and rationally engineered preQ1 riboswitches and their application to inducible gene regulation in mycobacteria. Because mycobacteria lack preQ1 biosynthetic genes, we hypothesized that preQ1 could be used as an exogenous nonmetabolite ligand to control riboswitches in mycobacteria. Selected naturally occurring preQ1 riboswitches were assayed and successfully drove preQ1-dependent repression of a green fluorescent protein reporter in Using structure-based design, we engineered three preQ1 riboswitches from , , and toward achieving higher response ratios and increased repression. Assuming a steady-state model, variants of the riboswitch most closely followed the predicted trends. Unexpectedly, the preQ1 dose response was best described by a model with a second, independent preQ1 binding site. This behavior was general to the preQ1 riboswitch family, since the wild type and rationally designed mutants of riboswitches from all three bacteria behaved analogously. Across all variants, the response ratios, which describe expression in the absence versus the presence of preQ1, ranged from <2 to ∼10, but repression in all cases was incomplete up to 1 mM preQ1. By reducing the transcript expression level, we obtained a preQ1 riboswitch variant appropriate for inducible knockdown applications. We further showed that the preQ1 response is reversible, is titratable, and can be used to control protein expression in mycobacteria within infected macrophages. By engineering naturally occurring preQ1 riboswitches, we have not only extended the tools available for inducible gene regulation in mycobacteria but also uncovered new behavior of these riboswitches. Riboswitches are elements found in noncoding regions of mRNA that regulate gene expression, typically in response to an endogenous metabolite. Riboswitches have emerged as important tools for inducible gene expression in diverse organisms. We noted that mycobacteria lack the biosynthesis genes for preQ1, a ligand for riboswitches from diverse bacteria. Predicting that preQ1 is not present in mycobacteria, we showed that it controls optimized riboswitches appropriate for gene knockdown applications. Further, the riboswitch response is subject to a second independent preQ1 binding event that has not been previously documented. By engineering naturally occurring riboswitches, we have uncovered a new behavior, with implications for riboswitch function in its native context, and extended the tools available for inducible gene regulation in mycobacteria.
[Mh] Termos MeSH primário: Regulação Bacteriana da Expressão Gênica
Mycobacterium smegmatis/metabolismo
Pirimidinonas
Pirróis
Riboswitch/fisiologia
[Mh] Termos MeSH secundário: Bacillus subtilis
Sequência de Bases
Engenharia Genética
Lactobacillus rhamnosus
Mycobacterium smegmatis/genética
Nucleosídeo Q/metabolismo
Riboswitch/genética
Thermoanaerobacter
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (7-(aminomethyl)-7-deazaguanine); 0 (Pyrimidinones); 0 (Pyrroles); 0 (Riboswitch); 57072-36-3 (Nucleoside Q)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170828
[Lr] Data última revisão:
170828
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170111
[St] Status:MEDLINE


  4 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
[PMID]:27754868
[Au] Autor:Jung J; Czabany T; Wilding B; Klempier N; Nidetzky B
[Ad] Endereço:From the Austrian Centre of Industrial Biotechnology, Petersgasse 14.
[Ti] Título:Kinetic Analysis and Probing with Substrate Analogues of the Reaction Pathway of the Nitrile Reductase QueF from Escherichia coli.
[So] Source:J Biol Chem;291(49):25411-25426, 2016 Dec 02.
[Is] ISSN:1083-351X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The enzyme QueF catalyzes a four-electron reduction of a nitrile group into an amine, the only reaction of this kind known in biology. In nature, QueF converts 7-cyano-7-deazaguanine (preQ ) into 7-aminomethyl-7-deazaguanine (preQ ) for the biosynthesis of the tRNA-inserted nucleoside queuosine. The proposed QueF mechanism involves a covalent thioimide adduct between preQ and a cysteine nucleophile in the enzyme, and this adduct is subsequently converted into preQ in two NADPH-dependent reduction steps. Here, we show that the Escherichia coli QueF binds preQ in a strongly exothermic process (ΔH = -80.3 kJ/mol; -TΔS = 37.9 kJ/mol, K = 39 nm) whereby the thioimide adduct is formed with half-of-the-sites reactivity in the homodimeric enzyme. Both steps of preQ reduction involve transfer of the 4-pro-R-hydrogen from NADPH. They proceed about 4-7-fold more slowly than trapping of the enzyme-bound preQ as covalent thioimide (1.63 s ) and are thus mainly rate-limiting for the enzyme's k (=0.12 s ). Kinetic studies combined with simulation reveal a large primary deuterium kinetic isotope effect of 3.3 on the covalent thioimide reduction and a smaller kinetic isotope effect of 1.8 on the imine reduction to preQ 7-Formyl-7-deazaguanine, a carbonyl analogue of the imine intermediate, was synthesized chemically and is shown to be recognized by QueF as weak ligand for binding (ΔH = -2.3 kJ/mol; -TΔS = -19.5 kJ/mol) but not as substrate for reduction or oxidation. A model of QueF substrate recognition and a catalytic pathway for the enzyme are proposed based on these data.
[Mh] Termos MeSH primário: Proteínas de Escherichia coli/química
Escherichia coli/enzimologia
Guanosina/análogos & derivados
Modelos Químicos
NADP/química
Nucleosídeo Q/análogos & derivados
Oxirredutases/química
[Mh] Termos MeSH secundário: Guanosina/química
Cinética
Nucleosídeo Q/química
Oxirredução
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (7-cyano-7-deazaguanosine); 0 (Escherichia coli Proteins); 12133JR80S (Guanosine); 53-59-8 (NADP); 57072-36-3 (Nucleoside Q); 66048-70-2 (7-aminomethyl-7-deazaguanosine); EC 1.- (Oxidoreductases); EC 1.- (QueF protein, E coli)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170526
[Lr] Data última revisão:
170526
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161019
[St] Status:MEDLINE


  5 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
[PMID]:27638883
[Au] Autor:Dowling DP; Miles ZD; Köhrer C; Maiocco SJ; Elliott SJ; Bandarian V; Drennan CL
[Ad] Endereço:Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
[Ti] Título:Molecular basis of cobalamin-dependent RNA modification.
[So] Source:Nucleic Acids Res;44(20):9965-9976, 2016 Nov 16.
[Is] ISSN:1362-4962
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Queuosine (Q) was discovered in the wobble position of a transfer RNA (tRNA) 47 years ago, yet the final biosynthetic enzyme responsible for Q-maturation, epoxyqueuosine (oQ) reductase (QueG), was only recently identified. QueG is a cobalamin (Cbl)-dependent, [4Fe-4S] cluster-containing protein that produces the hypermodified nucleoside Q in situ on four tRNAs. To understand how QueG is able to perform epoxide reduction, an unprecedented reaction for a Cbl-dependent enzyme, we have determined a series of high resolution structures of QueG from Bacillus subtilis Our structure of QueG bound to a tRNA anticodon stem loop shows how this enzyme uses a HEAT-like domain to recognize the appropriate anticodons and position the hypermodified nucleoside into the enzyme active site. We find Q bound directly above the Cbl, consistent with a reaction mechanism that involves the formation of a covalent Cbl-tRNA intermediate. Using protein film electrochemistry, we show that two [4Fe-4S] clusters adjacent to the Cbl have redox potentials in the range expected for Cbl reduction, suggesting how Cbl can be activated for nucleophilic attack on oQ. Together, these structural and electrochemical data inform our understanding of Cbl dependent nucleic acid modification.
[Mh] Termos MeSH primário: Processamento Pós-Transcricional do RNA
RNA de Transferência/química
RNA de Transferência/genética
Vitamina B 12/química
[Mh] Termos MeSH secundário: Anticódon
Bacillus subtilis/genética
Ligações de Hidrogênio
Ferro/química
Modelos Moleculares
Conformação Molecular
Conformação de Ácido Nucleico
Nucleosídeo Q/análogos & derivados
Nucleosídeo Q/química
Ligação Proteica
Estabilidade de RNA
RNA Bacteriano/química
RNA Bacteriano/genética
RNA Bacteriano/metabolismo
RNA de Transferência/metabolismo
Ribonucleases/química
Ribonucleases/metabolismo
Enxofre/química
Vitamina B 12/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anticodon); 0 (RNA, Bacterial); 107865-20-3 (nucleoside oQ); 57072-36-3 (Nucleoside Q); 70FD1KFU70 (Sulfur); 9014-25-9 (RNA, Transfer); E1UOL152H7 (Iron); EC 3.1.- (Ribonucleases); P6YC3EG204 (Vitamin B 12)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170606
[Lr] Data última revisão:
170606
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160918
[St] Status:MEDLINE


  6 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:26378237
[Au] Autor:Payne KA; Fisher K; Sjuts H; Dunstan MS; Bellina B; Johannissen L; Barran P; Hay S; Rigby SE; Leys D
[Ad] Endereço:From the Manchester Institute of Biotechnology, University of Manchester, Princess Street 131, Manchester M1 7DN, United Kingdom karl.payne@manchester.ac.uk.
[Ti] Título:Epoxyqueuosine Reductase Structure Suggests a Mechanism for Cobalamin-dependent tRNA Modification.
[So] Source:J Biol Chem;290(46):27572-81, 2015 Nov 13.
[Is] ISSN:1083-351X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Queuosine (Q) is a hypermodified RNA base that replaces guanine in the wobble positions of 5'-GUN-3' tRNA molecules. Q is exclusively made by bacteria, and the corresponding queuine base is a micronutrient salvaged by eukaryotic species. The final step in Q biosynthesis is the reduction of the epoxide precursor, epoxyqueuosine, to yield the Q cyclopentene ring. The epoxyqueuosine reductase responsible, QueG, shares distant homology with the cobalamin-dependent reductive dehalogenase (RdhA), however the role played by cobalamin in QueG catalysis has remained elusive. We report the solution and structural characterization of Streptococcus thermophilus QueG, revealing the enzyme harbors a redox chain consisting of two [4Fe-4S] clusters and a cob(II)alamin in the base-off form, similar to RdhAs. In contrast to the shared redox chain architecture, the QueG active site shares little homology with RdhA, with the notable exception of a conserved Tyr that is proposed to function as a proton donor during reductive dehalogenation. Docking of an epoxyqueuosine substrate suggests the QueG active site places the substrate cyclopentane moiety in close proximity of the cobalt. Both the Tyr and a conserved Asp are implicated as proton donors to the epoxide leaving group. This suggests that, in contrast to the unusual carbon-halogen bond chemistry catalyzed by RdhAs, QueG acts via Co-C bond formation. Our study establishes the common features of Class III cobalamin-dependent enzymes, and reveals an unexpected diversity in the reductive chemistry catalyzed by these enzymes.
[Mh] Termos MeSH primário: Nucleosídeo Q/análogos & derivados
Nucleosídeo Q/biossíntese
Oxirredutases/química
RNA de Transferência/química
Streptococcus thermophilus/enzimologia
Vitamina B 12/química
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Catálise
Cobalto/química
Cristalografia por Raios X
Halogenação
Dados de Sequência Molecular
Nucleosídeo Q/química
Oxirredução
Oxirredutases/genética
Estrutura Secundária de Proteína
Soluções
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Solutions); 107865-20-3 (nucleoside oQ); 3G0H8C9362 (Cobalt); 57072-36-3 (Nucleoside Q); 9014-25-9 (RNA, Transfer); EC 1.- (Oxidoreductases); P6YC3EG204 (Vitamin B 12)
[Em] Mês de entrada:1603
[Cu] Atualização por classe:171110
[Lr] Data última revisão:
171110
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150918
[St] Status:MEDLINE
[do] DOI:10.1074/jbc.M115.685693


  7 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:26230193
[Au] Autor:Miles ZD; Myers WK; Kincannon WM; Britt RD; Bandarian V
[Ad] Endereço:†Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.
[Ti] Título:Biochemical and Spectroscopic Studies of Epoxyqueuosine Reductase: A Novel Iron-Sulfur Cluster- and Cobalamin-Containing Protein Involved in the Biosynthesis of Queuosine.
[So] Source:Biochemistry;54(31):4927-35, 2015 Aug 11.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Queuosine is a hypermodified nucleoside present in the wobble position of tRNAs with a 5'-GUN-3' sequence in their anticodon (His, Asp, Asn, and Tyr). The 7-deazapurine core of the base is synthesized de novo in prokaryotes from guanosine 5'-triphosphate in a series of eight sequential enzymatic transformations, the final three occurring on tRNA. Epoxyqueuosine reductase (QueG) catalyzes the final step in the pathway, which entails the two-electron reduction of epoxyqueuosine to form queuosine. Biochemical analyses reveal that this enzyme requires cobalamin and two [4Fe-4S] clusters for catalysis. Spectroscopic studies show that the cobalamin appears to bind in a base-off conformation, whereby the dimethylbenzimidazole moiety of the cofactor is removed from the coordination sphere of the cobalt but not replaced by an imidazole side chain, which is a hallmark of many cobalamin-dependent enzymes. The bioinformatically identified residues are shown to have a role in modulating the primary coordination sphere of cobalamin. These studies provide the first demonstration of the cofactor requirements for QueG.
[Mh] Termos MeSH primário: Bacillus subtilis
Proteínas de Bactérias
Proteínas com Ferro-Enxofre
Nucleosídeo Q
Oxirredutases
Vitamina B 12
[Mh] Termos MeSH secundário: Bacillus subtilis/química
Bacillus subtilis/genética
Bacillus subtilis/metabolismo
Proteínas de Bactérias/química
Proteínas de Bactérias/genética
Proteínas de Bactérias/metabolismo
Catálise
Proteínas com Ferro-Enxofre/química
Proteínas com Ferro-Enxofre/genética
Proteínas com Ferro-Enxofre/metabolismo
Nucleosídeo Q/biossíntese
Nucleosídeo Q/química
Nucleosídeo Q/genética
Oxirredutases/química
Oxirredutases/genética
Oxirredutases/metabolismo
Vitamina B 12/química
Vitamina B 12/genética
Vitamina B 12/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Iron-Sulfur Proteins); 57072-36-3 (Nucleoside Q); EC 1.- (Oxidoreductases); P6YC3EG204 (Vitamin B 12)
[Em] Mês de entrada:1510
[Cu] Atualização por classe:170714
[Lr] Data última revisão:
170714
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150801
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.5b00335


  8 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:26106162
[Au] Autor:Liberman JA; Suddala KC; Aytenfisu A; Chan D; Belashov IA; Salim M; Mathews DH; Spitale RC; Walter NG; Wedekind JE
[Ad] Endereço:Department of Biochemistry and Biophysics, and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642;
[Ti] Título:Structural analysis of a class III preQ1 riboswitch reveals an aptamer distant from a ribosome-binding site regulated by fast dynamics.
[So] Source:Proc Natl Acad Sci U S A;112(27):E3485-94, 2015 Jul 07.
[Is] ISSN:1091-6490
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:PreQ1-III riboswitches are newly identified RNA elements that control bacterial genes in response to preQ1 (7-aminomethyl-7-deazaguanine), a precursor to the essential hypermodified tRNA base queuosine. Although numerous riboswitches fold as H-type or HLout-type pseudoknots that integrate ligand-binding and regulatory sequences within a single folded domain, the preQ1-III riboswitch aptamer forms a HLout-type pseudoknot that does not appear to incorporate its ribosome-binding site (RBS). To understand how this unusual organization confers function, we determined the crystal structure of the class III preQ1 riboswitch from Faecalibacterium prausnitzii at 2.75 Å resolution. PreQ1 binds tightly (KD,app 6.5 ± 0.5 nM) between helices P1 and P2 of a three-way helical junction wherein the third helix, P4, projects orthogonally from the ligand-binding pocket, exposing its stem-loop to base pair with the 3' RBS. Biochemical analysis, computational modeling, and single-molecule FRET imaging demonstrated that preQ1 enhances P4 reorientation toward P1-P2, promoting a partially nested, H-type pseudoknot in which the RBS undergoes rapid docking (kdock ∼ 0.6 s(-1)) and undocking (kundock ∼ 1.1 s(-1)). Discovery of such dynamic conformational switching provides insight into how a riboswitch with bipartite architecture uses dynamics to modulate expression platform accessibility, thus expanding the known repertoire of gene control strategies used by regulatory RNAs.
[Mh] Termos MeSH primário: Aptâmeros de Nucleotídeos/genética
RNA Bacteriano/genética
Ribossomos/genética
Riboswitch/genética
[Mh] Termos MeSH secundário: Aptâmeros de Nucleotídeos/química
Aptâmeros de Nucleotídeos/metabolismo
Sequência de Bases
Sítios de Ligação/genética
Clostridium/genética
Clostridium/metabolismo
Cristalografia por Raios X
Cinética
Simulação de Dinâmica Molecular
Dados de Sequência Molecular
Nucleosídeo Q/química
Nucleosídeo Q/metabolismo
Pirimidinonas/química
Pirimidinonas/metabolismo
Pirróis/química
Pirróis/metabolismo
Dobramento de RNA
RNA Bacteriano/química
RNA Bacteriano/metabolismo
Ribossomos/metabolismo
Termodinâmica
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (7-(aminomethyl)-7-deazaguanine); 0 (Aptamers, Nucleotide); 0 (Pyrimidinones); 0 (Pyrroles); 0 (RNA, Bacterial); 0 (Riboswitch); 57072-36-3 (Nucleoside Q)
[Em] Mês de entrada:1510
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150625
[St] Status:MEDLINE
[do] DOI:10.1073/pnas.1503955112


  9 / 96 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:25884661
[Au] Autor:Fergus C; Barnes D; Alqasem MA; Kelly VP
[Ad] Endereço:School of Biochemistry & Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, 152-160 Pearse Street, Dublin 2, Ireland. cfergus@tcd.ie.
[Ti] Título:The queuine micronutrient: charting a course from microbe to man.
[So] Source:Nutrients;7(4):2897-929, 2015 Apr 15.
[Is] ISSN:2072-6643
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:Micronutrients from the diet and gut microbiota are essential to human health and wellbeing. Arguably, among the most intriguing and enigmatic of these micronutrients is queuine, an elaborate 7-deazaguanine derivative made exclusively by eubacteria and salvaged by animal, plant and fungal species. In eubacteria and eukaryotes, queuine is found as the sugar nucleotide queuosine within the anticodon loop of transfer RNA isoacceptors for the amino acids tyrosine, asparagine, aspartic acid and histidine. The physiological requirement for the ancient queuine molecule and queuosine modified transfer RNA has been the subject of varied scientific interrogations for over four decades, establishing relationships to development, proliferation, metabolism, cancer, and tyrosine biosynthesis in eukaryotes and to invasion and proliferation in pathogenic bacteria, in addition to ribosomal frameshifting in viruses. These varied effects may be rationalized by an important, if ill-defined, contribution to protein translation or may manifest from other presently unidentified mechanisms. This article will examine the current understanding of queuine uptake, tRNA incorporation and salvage by eukaryotic organisms and consider some of the physiological consequence arising from deficiency in this elusive and lesser-recognized micronutrient.
[Mh] Termos MeSH primário: Guanina/análogos & derivados
Micronutrientes/metabolismo
[Mh] Termos MeSH secundário: Envelhecimento
Animais
Modelos Animais de Doenças
Microbioma Gastrointestinal
Trato Gastrointestinal/microbiologia
Guanina/metabolismo
Guanina/farmacocinética
Seres Humanos
Mitocôndrias/metabolismo
Neoplasias/tratamento farmacológico
Nucleosídeo Q/metabolismo
RNA de Transferência/metabolismo
Traduções
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; REVIEW
[Nm] Nome de substância:
0 (Micronutrients); 57072-36-3 (Nucleoside Q); 5Z93L87A1R (Guanine); 72496-59-4 (queuine); 9014-25-9 (RNA, Transfer)
[Em] Mês de entrada:1601
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150418
[St] Status:MEDLINE
[do] DOI:10.3390/nu7042897


  10 / 96 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:25489848
[Au] Autor:Zaborske JM; DuMont VL; Wallace EW; Pan T; Aquadro CF; Drummond DA
[Ad] Endereço:Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America.
[Ti] Título:A nutrient-driven tRNA modification alters translational fidelity and genome-wide protein coding across an animal genus.
[So] Source:PLoS Biol;12(12):e1002015, 2014 Dec.
[Is] ISSN:1545-7885
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Natural selection favors efficient expression of encoded proteins, but the causes, mechanisms, and fitness consequences of evolved coding changes remain an area of aggressive inquiry. We report a large-scale reversal in the relative translational accuracy of codons across 12 fly species in the Drosophila/Sophophora genus. Because the reversal involves pairs of codons that are read by the same genomically encoded tRNAs, we hypothesize, and show by direct measurement, that a tRNA anticodon modification from guanosine to queuosine has coevolved with these genomic changes. Queuosine modification is present in most organisms but its function remains unclear. Modification levels vary across developmental stages in D. melanogaster, and, consistent with a causal effect, genes maximally expressed at each stage display selection for codons that are most accurate given stage-specific queuosine modification levels. In a kinetic model, the known increased affinity of queuosine-modified tRNA for ribosomes increases the accuracy of cognate codons while reducing the accuracy of near-cognate codons. Levels of queuosine modification in D. melanogaster reflect bioavailability of the precursor queuine, which eukaryotes scavenge from the tRNAs of bacteria and absorb in the gut. These results reveal a strikingly direct mechanism by which recoding of entire genomes results from changes in utilization of a nutrient.
[Mh] Termos MeSH primário: Drosophila/genética
Genoma de Inseto
Nucleosídeo Q/metabolismo
Fases de Leitura Aberta/genética
Biossíntese de Proteínas
RNA de Transferência/metabolismo
[Mh] Termos MeSH secundário: Animais
Anticódon/genética
Sequência de Bases
Códon
Drosophila melanogaster/genética
Cinética
Modelos Genéticos
Dados de Sequência Molecular
Nucleosídeo Q/química
Filogenia
Seleção Genética
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Anticodon); 0 (Codon); 57072-36-3 (Nucleoside Q); 9014-25-9 (RNA, Transfer)
[Em] Mês de entrada:1507
[Cu] Atualização por classe:170224
[Lr] Data última revisão:
170224
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:141210
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pbio.1002015



página 1 de 10 ir para página                        
   


Refinar a pesquisa
  Base de dados : MEDLINE Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde