共查询到20条相似文献,搜索用时 31 毫秒
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Taehee Kang Nam Hoon Kwon Jin Young LeeMin Chul Park Eunji KangHyo Hyun Kim Taek Jin KangSunghoon Kim 《Journal of molecular biology》2012,423(4):475-481
Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMPs) are nonenzymatic scaffolding proteins that comprise multisynthetase complex (MSC) with nine aminoacyl-tRNA synthetases in higher eukaryotes. Among the three AIMPs, AIMP3/p18 is strongly anchored to methionyl-tRNA synthetase (MRS) in the MSC. MRS attaches methionine (Met) to initiator tRNA (tRNAiMet) and plays an important role in translation initiation. It is known that AIMP3 is dispatched to nucleus or nuclear membrane to induce DNA damage response or senescence; however, the role of AIMP3 in translation as a component of MSC and the meaning of its interaction with MRS are still unclear. Herein, we observed that AIMP3 specifically interacted with Met-tRNAiMetin vitro, while it showed little or reduced interaction with unacylated or lysine-charged tRNAiMet. In addition, AIMP3 discriminates Met-tRNAiMet from Met-charged elongator tRNA based on filter-binding assay. Pull‐down assay revealed that AIMP3 and MRS had noncompetitive interaction with eukaryotic initiation factor 2 (eIF2) γ subunit (eIF2γ), which is in charge of binding with Met-tRNAiMet for the delivery of Met-tRNAiMet to ribosome. AIMP3 recruited active eIF2γ to the MRS-AIMP3 complex, and the level of Met-tRNAiMet bound to eIF2 complex was reduced by AIMP3 knockdown resulting in reduced protein synthesis. All these results suggested the novel function of AIMP3 as a critical mediator of Met-tRNAiMet transfer from MRS to eIF2 complex for the accurate and efficient translation initiation. 相似文献
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Mengovirus RNA was translated in Ehrlich ascites cell extracts using as radioactive precursors f[35S]Met tRNAFMet and [35S]Met tRNAMMet to label the products in N-terminal and internal positions, respectively. Tryptic peptides were compared with those derived from purified [35S]Met-labeled mengovirus. The results indicate that the sequences corresponding to the viral coat polypeptides are preceded by a short “lead-in” peptide which is probably removed by a cleavage process in infected cells. 相似文献
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The initiator methionine transfer RNA (tRNAf
Met) gene was identified on a 347 bpEco RI-Hind III DNA fragment of the potato mitochondrial (mt) genome. The sequence of this gene shows 1 to 7 nucleotide differences with the other plant mt tRNAsf
Met or tRNAf
Met genes studied so far. Whereas the tRNAf
Met gene is present as a single copy in the potato mt genome, a tRNA pseudogene corresponding to 60% of a complete tRNA (from the 5 end to the variable region) and located at 105 nucleotides upstream of the tRNAf
Met gene on the opposite strand was shown to be repeated at least three times. Furthermore, the physical environment of the tRNAf
Met gene in the mt genome is very different among plants, which suggests that the tRNAf
Met gene region has often been implicated in recombination events of plant mt genomes leading to important rearrangements in gene order. 相似文献
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Laurence Marechal Pierre Guillemaut Jean-Michel Grienenberger Geneviève Jeannin Jacques-Henry Weil 《Plant molecular biology》1986,7(4):245-253
Summary Two bean mitochondria methionine transfer RNAs, purified by RPC-5 chromatography and two-dimensional gel electrophoresis, have been sequenced usingin vitro post-labeling techniques.One of these tRNAsMet has been identified by formylation using anE. coli enzyme as the mitochondrial tRNAF
Met. It displays strong structural homologies with prokaryotic and chloroplast tRNAF
Met sequences (70.1–83.1%) and with putative initiator tRNAm
Met genes described for wheat, maize andOenothera mitochondrial genomes (88.3–89.6%).The other tRNAMet, which is the mitochondrial elongator tRNAF
Met, shows a high degree of sequence homology (93.3–96%& with chloroplast tRNAm
Met, but a weak homology (40.7%) with a sequenced maize mitochondrial putative elongator tRNAm
Met gene.Bean mitochondrial tRNAF
Met and tRNAm
Met were hybridized to Southern blots of the mitochondrial genomes of wheat and maize, whose maps have been recently published (15, 22), in order to locate the position of their genes. 相似文献
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Genomic size of animal mitochondrial DNA is usually minimized over time. Thus, when regional duplications occur, they are followed by a rapid elimination of redundant material. In contrast to this general view, we report here long-sustained tRNA pseudogenes in the mitochondrial genome (mitogenome) of teleost fishes of the family Scaridae (parrotfishes). During the course of a molecular phylogenetic study of the suborder Labroidei, we determined the complete nucleotide sequence of the mitogenome for a parrotfish, Chlorurus sordidus, and found a gene rearrangement accompanied by a tRNA pseudogene. In the typical gene order of vertebrates, a tRNA-gene cluster between ND1 and ND2 genes includes tRNAIle (I), tRNAGln (Q), and tRNAMet (M) genes in this order (IQM). However, in the mitogenome of the parrotfish, the tRNAMet gene was inserted between the tRNAIle and the tRNAGln genes, and the tRNAGln gene was followed by a putative tRNAMet pseudogene (M). Such a tRNA gene rearrangement including a pseudogene (IMQM) was found in all of the 10 examined species, representing 7 of the 10 currently recognized scarid genera. All sister groups examined (20 species of Labridae and a single species of Odacidae) had the typical gene order of vertebrate mitogenomes. Phylogenetic analysis of the tRNAMet genes and the resulting pseudogenes demonstrated that the ancestral tRNAMet gene was duplicated in a common ancestor of the parrotfish. Based on the fossil record, these results indicate that the pseudogenes have survived at least 14 million years. Most of the vertebrate mitochondrial gene rearrangements involving the IQM region have held the tRNAMet gene just upstream of the ND2 gene, and even in a few exceptional cases, including the present ones, the tRNA pseudogenes have been found in that position. In addition, most of these tRNAMet pseudogenes maintained clover-leaf secondary structures, with the remainder sustaining the clover-leaf structure in the top half (TC and acceptor arms). Considering their potential secondary structures (holding top halves of the clover-leaf structures), locations within mitogenomes (flanking the 5 ends of the ND2 genes) and stabilities over time (survived at least 14 Myr), it is likely that the tRNA pseudogenes retain function as punctuation marks for mitochondrial ND2 mRNA processing.This article contains online supplementary material.Reviewing Editor: Dr. Axel Meyer 相似文献
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Translational nonsense codon suppression as indicator for functional pre-tRNA splicing in transformed Arabidopsis hypocotyl-derived calli 总被引:1,自引:1,他引:0 下载免费PDF全文
The transient expression of three novel plant amber suppressors derived from a cloned Nicotiana tRNASer(CGA), an Arabidopsis intron-containing tRNATyr(GTA) and an Arabidopsis intron-containing tRNAMet(CAT) gene, respectively, was studied in a homologous plant system that utilized the Agro bacterium-mediated gene transfer to Arabidopsis hypocotyl explants. This versatile system allows the detection of β-glucuronidase (GUS) activity by histochemical and enzymatic analyses. The activity of the suppressors was demonstrated by the ability to suppress a premature amber codon in a modified GUS gene. Co-transformation of Arabidopsis hypocotyls with the amber suppressor tRNASer gene and the GUS reporter gene resulted in ~10% of the GUS activity found in the same tissue transformed solely with the functional control GUS gene. Amber suppressor tRNAs derived from intron-containing tRNATyr or tRNAMet genes were functional in vivo only after some additional gene manipulations. The G3:C70 base pair in the acceptor stem of tRNAMet(CUA) had to be converted to a G3:U70 base pair, which is the major determinant for alanine tRNA identity. The inability of amber suppressor tRNATyr to show any activity in vivo predominantly results from a distorted intron secondary structure of the corresponding pre-tRNA that could be cured by a single nucleotide exchange in the intervening sequence. The improved amber suppressors tRNATyr and tRNAMet were subsequently employed for studying various aspects of the plant-specific mechanism of pre-tRNA splicing as well as for demonstrating the influence of intron-dependent base modifications on suppressor activity. 相似文献
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Intron-containing tRNA genes are exceptional within nuclear plant genomes. It appears that merely two tRNA gene families coding for tRNATyr
G A and elongator tRNAMet
CmAU contain intervening sequences. We have previously investigated the features required by wheat germ splicing endonuclease for efficient and accurate intron excision from Arabidopsis pre-tRNATyr. Here we have studied the expression of an Arabidopsis elongator tRNAMet gene in two plant extracts of different origin. This gene was first transcribed either in HeLa or in tobacco cell nuclear extract and splicing of intron-containing tRNAMet precursors was then examined in wheat germ S23 extract and in the tobacco system. The results show that conversion of pre-tRNAMet to mature tRNA proceeds very efficiently in both plant extracts. In order to elucidate the potential role of specific nucleotides at the 3 and 5 splice sites and of a structured intron for pre-tRNAMet splicing in either extract, we have performed a systematic survey by mutational analyses. The results show that cytidine residues at intron-exon boundaries impair pre-tRNAMet splicing and that a highly structured intron is indispensable for pre-tRNAMet splicing. tRNA precursors with an extended anticodon stem of three to four base pairs are readily accepted as substrates by wheat and tobacco splicing endonuclease, whereas pre-tRNA molecules that can form an extended anticodon stem of only two putative base pairs are not spliced at all. An amber suppressor, generated from the intron-containing elongator tRNAMet gene, is efficiently processed and spliced in both plant extracts. 相似文献
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Diego Rojas-Benitez Patrick C. Thiaville Valérie de Crécy-Lagard Alvaro Glavic 《The Journal of biological chemistry》2015,290(30):18699-18707
N6-Threonylcarbamoyl-adenosine (t6A) is a universal modification occurring at position 37 in nearly all tRNAs that decode A-starting codons, including the eukaryotic initiator tRNA (tRNAiMet). Yeast lacking central components of the t6A synthesis machinery, such as Tcs3p (Kae1p) or Tcs5p (Bud32p), show slow-growth phenotypes. In the present work, we show that loss of the Drosophila tcs3 homolog also leads to a severe reduction in size and demonstrate, for the first time in a non-microbe, that Tcs3 is required for t6A synthesis. In Drosophila and in mammals, tRNAiMet is a limiting factor for cell and animal growth. We report that the t6A-modified form of tRNAiMet is the actual limiting factor. We show that changing the proportion of t6A-modified tRNAiMet, by expression of an un-modifiable tRNAiMet or changing the levels of Tcs3, regulate target of rapamycin (TOR) kinase activity and influences cell and animal growth in vivo. These findings reveal an unprecedented relationship between the translation machinery and TOR, where translation efficiency, limited by the availability of t6A-modified tRNA, determines growth potential in eukaryotic cells. 相似文献
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