Structure Of tRNA Research Articles

Effects of polyamines from Thermus thermophilus, an extreme-thermophilic eubacterium, on tRNA methylation by tRNA (Gm18) methyltransferase (TrmH).

Thermus thermophilus is an extreme-thermophilic eubacterium, which grows at a wide range of temperatures (50-83°C). This thermophile produces various polyamines including long and branched polyamines. In tRNAs from T. thermophilus, three distinct modifications, 2'-O-methylguanosine at position 18 (Gm18), 5-methyl-2-thiouridine at position 54 and N(1)-methyladenosine at position 58, are assembled at the elbow region to stabilize the L-shaped tRNA structure. However, the structures of unmodified tRNA precursors are disrupted at high temperatures. We hypothesize that polyamine(s) might have a positive effect on the modification process of unmodified tRNA transcript. We investigated the effects of eight polyamines on Gm18 formation in the yeast tRNA(Phe) transcript by tRNA (Gm18) methyltransferase (TrmH). Higher concentrations of linear polyamines inhibited TrmH activity at 55°C, while optimum concentration increased TrmH activity at 45-75°C. Exceptionally, caldohexamine, a long polyamine, did not show any positive effect on the TrmH activity at 55°C. However, temperature-dependent experiments revealed that 1 mM caldohexamine increased TrmH activity at 60-80°C. Furthermore, 0.25 mM tetrakis(3-aminopropy)ammonium, a branched polyamine, increased TrmH activity at a broad range of temperatures (40-85°C). Thus, caldohexamine and tetrakis(3-aminopropy)ammonium were found to enhance the TrmH activity at high temperatures.

Complete mitochondrial genome of black-banded trevally (Seriolina nigrofasciata): Genome characterization and phylogenetic considerations

The black-banded trevally (Seriolina nigrofasciata) is a species of the family Carangidae and the only known member of genus Seriolina. To understand the phylogenetic relationship of black-banded trevally in teleost, we first determined the complete mitochondrial genome of black-banded trevally. The entire mitochondrial genome of black-banded trevally is 16 531 bp in length, containing 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNAs), and 2 main non-coding regions. The overall base composition is T 25.8%, C 30.0%, A 26.7%, and G 17.5%. The gene arrangement, base composition, and tRNA structures of black-banded trevally are consistent with those of other teleost. Two of the central conserved sequence blocks (CSB-2 and CSB-3) were identified and the core sequence (TACATGTATGTA) of terminal-associated sequences was recognized in the control region. Meanwhile, the conserved motif 5′-GCCGG-3′ was identified in the origin of light-strand replication of black-banded trevally. The complete mitochondrial genome of black-banded trevally was used to construct phylogenetic tree, which shows that black-banded trevally is clustered with the fishes of the genus Seriola. We expect that the availability of the mitochondrial genome of black-banded trevally will facilitate the further investigations of molecular systematic and phylogenetic analysis of the Carangidae.

Description of a species of Fabaeformiscandona (Ostracoda, Crustacea) from Kushiro Marsh, Hokkaido, Japan, with the nearly complete mitochondrial genomic sequence.

BackgroundSo far, 16 species of non-marine ostracods have been reported from Kushiro Marsh, Kushiro Shitsugen National Park, eastern Hokkaido, Japan (Hiruta and Smith 2001, Smith and Hiruta 2004). Nine of these species are in Candonidae, the second-most diverse family of non-marine ostracods. This family contains ca. 550 species, or around 25% of the total number of non-marine ostracod species (Martens et al. 2008).New informationWe sampled ostracods in Kushiro Marsh on 27 December 2012 and identified an undescribed species in the family Candonidae, herein described as Fabaeformiscandona kushiroensis sp. nov. This species belongs to the F. acuminata species group and is characterized by the shapes of the elongate, dorsally directed medial and outer lobes on the distal end of each hemipenis. We also determined for this species the sequence of the nearly complete mitochondrial genome, the first record from the order Podocopa. The genome (ca. 17 kbp) contains two ribosomal RNA, 22 transfer RNA, and 13 protein-coding genes, as also found in other arthropods for which the mitochondrial genome has been sequenced. The gene arrangement is similar to the pancrustacean ground pattern, except that in the control region there is an approximately 2 kbp tandem repeat region composed of 220-bp motif sequences. We describe the genetic features of the mitochondrial genome, including nucleotide composition and the secondary structures of tRNAs and rRNAs, and compare them with the genome of Vargula hilgendorfii (Myodocopa, Ostracoda).

Sodium chloride-induced conformational change in tRNA as measured by circular dichroism

Abstract The effect of 0.01-1 M sodium ions on the conformation of the folded brewer’s yeast tRNAPhe was examined by circular dichroism method in the region 200-350 nm. The minimum peak at about 210 nm for tRNA solution with 50 mM sodium chloride showed a decrease in magnitude by 26-30% in comparison to that recorded for the solution of higher NaCl content. The depths of the peaks at 225 nm and 233 nm for two solutions with the lowest sodium chloride concentrations (cNaCl = 10mM, cNaCl = 50mM) were changed by 3-10% relative to the those in the spectra of other samples, for the 260 nm maximum peak a decrease in height was 21-25%. In the region 300-350 nm no significant difference was observed. The results point to a strong relationship between concentration of sodium ions and stabilization process of secondary and tertiary tRNA structure, which indicates the influence of sodium ions on stacking and base-pairing interactions.

Theoretical Search for RNA Folding Nuclei

The functions of RNA molecules are defined by their spatial structure, whose folding is regulated by numerous factors making RNA very similar to proteins. Prediction of RNA folding nuclei gives the possibility to take a fresh look at the problems of the multiple folding pathways of RNA molecules and RNA stability. The algorithm previously developed for prediction of protein folding nuclei has been successfully applied to ~150 various RNA structures: hairpins, tRNAs, structures with pseudoknots, and the large structured P4-P6 domain of the Tetrahymena group I intron RNA. The calculated Φ-values for tRNA structures agree with the experimental data obtained earlier. According to the experiment the nucleotides of the D and T hairpin loops are the last to be involved in the tRNA tertiary structure. Such agreement allowed us to do a prediction for an example of large structured RNA, the P4-P6 RNA domain. One of the advantages of our method is that it allows us to make predictions about the folding nucleus for nontrivial RNA motifs: pseudoknots and tRNA.

The complete mitochondrial genome of Plodia interpunctella (Lepidoptera: Pyralidae) and comparison with other Pyraloidea insects.

The mitochondrial (mt) genome can provide important information for the understanding of phylogenetic relationships. The complete mt genome of Plodia interpunctella (Lepidoptera: Pyralidae) has been sequenced. The circular genome is 15 287 bp in size, encoding 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a control region. The AT skew of this mt genome is slightly negative, and the nucleotide composition is biased toward A+T nucleotides (80.15%). All PCGs start with the typical ATN (ATA, ATC, ATG, and ATT) codons, except for the cox1 gene which may start with the CGA codon. Four of the 13 PCGs harbor the incomplete termination codon T or TA. All the tRNA genes are folded into the typical clover-leaf structure of mitochondrial tRNA, except for trnS1 (AGN) in which the DHU arm fails to form a stable stem-loop structure. The overlapping sequences are 35 bp in total and are found in seven different locations. A total of 240 bp of intergenic spacers are scattered in 16 regions. The control region of the mt genome is 327 bp in length and consisted of several features common to the sequenced lepidopteran insects. Phylogenetic analysis based on 13 PCGs using the Maximum Likelihood method shows that the placement of P. interpunctella was within the Pyralidae.

Characteristics and phylogenetic analysis of the complete mitochondrial genome of Cheilodactylus quadricornis (Perciformes, Cheilodactylidae)

The complete mitochondrial genome of the Cheilodactylus quadricornis was firstly determined in the present study. The mitochondrial genome of C. quadricornis is 16 521 nucleotides, comprising 13 protein-coding genes and 2 ribosomal RNA genes, 22 tRNA genes and 2 main non-coding regions (the control region and the origin of the light-strand replication). The overall base composition was T, 26.3%; C, 29.6%; A, 27.8% and G, 16.3%. The gene arrangement, base composition, and tRNA structures of the complete mitochondrial genome of C. quadricornis is similar to other teleosts. Only two central conserved sequence blocks (CSB-2 and CSB-3) were identified in the control region. In addition, the conserved motif 5′-GCCGG-3′ was identified in the origin of light-strand replication of C. quadricornis. The complete mitochondrial genome of C. quadricornis was used to construct phylogenetic tree, which shows that C. quadricornis and C. variegatus clustered in a clade and formed a sister relationship. This mitogenome sequence data would play an important role in population genetics and phylogenetic analysis of the Cheilodactylidae.

The first complete mitochondrial genome of Serranidae sp. (Percoidea, Serranidae) and phylogenetic analysis based on Bayesian

In the present study, the complete mitochondrial genome of Serranidae sp. was determined first. The entire mitochondrial genome of Serranidae sp. is 16 512 bp in length, containing 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNA) and 2 main non-coding regions (the control region and the origin of the light-strand replication). The gene arrangement, base composition and tRNA structures of Serranidae sp. are similar to most of the bony fishes. The central conserved sequence blocks (CSB-1, CSB-2, and CSB-3) and the core sequence (ACATATATGT) of terminal-associated sequences were recognized in the control region. Meanwhile, the conserved motif 5′-GCCGG-3′ was identified in the origin of light-strand replication of Serranidae sp. Phylogenetic tree, which is constructed based on the complete mitochondrial genome sequences of Serranidae sp., shows that Serranidae sp. is clustered with the fishes of the family Pentacerotidae. We expect that the mitochondrial genome of Serranidae sp. would play a key role in phylogenetic analysis of Serranidae.

Complete mitochondrial genome of banjofish (Banjos banjos): genome characterization and phylogenetic analysis

The banjofish (Banjos banjos) is the only species in the monotypic genus Banjos and in the family Banjosidae. To understand the phylogenetic relationship of banjofish in teleost, we firstly determined the complete mitochondrial genome of banjofish. The entire mitochondrial genome of banjofish is 16 485 bp in length, including 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNA) and a control region (CR). The overall base composition is T, 26.2%; C, 29.2%; A, 28.6% and G, 16.0%. The central conserved sequence blocks (CSB) were identified and the core sequence (ACATATATGT) of terminal-associated sequences was recognized in the control region. The gene arrangement, base composition, and tRNA structures of the complete mitochondrial genome of banjofish is consistent with those of other teleost. The complete mitochondrial genome of banjofish was used to construct phylogenetic tree, which shows that banjofish is clustered with the fishes of the family Histiopteridae. We expect that the availability of mitochondrial genome of banjofish will facilitate the further investigations of the taxonomic resolution, biogeography and molecular systematic.

The complete mitochondrial genome of Eriocheir japonica sinensis (Decapoda: Varunidae) and its phylogenetic analysis

The complete mitochondrial genome (mitogenome) can provide novel insights into understanding the mechanisms underlying mitogenome evolution. In this study, the complete mitogenome of Eriocheir japonica sinensis (Decapoda: Varunidae) was determined to be 16,378 bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a D-loop region. The AT skew of the E. j. sinensis mitogenome was slightly negative (−0.016), indicating a higher number of T compared with A nucleotides. The nucleotide composition of the mitogenome was also biased toward A + T nucleotides (71.6%). All PCGs were initiated by ATN codons. Eight of the 13 PCGs harbored the incomplete termination codon by T, or TA. All other tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The D-loop region of the E. j. sinensis mitogenome was 918 bp in length. Based on 13 PCGs, phylogenetic analysis confirmed the placement of E. j. sinensis within the Varunidae.

Complete mitochondrial genome of the urohaze-goby Glossogobius olivaceus (Perciformes, Gobiidae) and structure comparison of light strand replication origin in Gobioidei

The genome of Glossogobius olivaceus (G. olivaceus) was 16,568 bp in length with a standard set of 13 protein-coding genes, 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs) and 2 non-coding region (the control region and origin of the light strand replication). The conserved motif 5′-GCCGG-3′ was determined in the origin of light strand replication of G. olivaceus. The G. olivaceus mitogenome base composition was: T 25.65%, C 29.82% A 27.17% and G 17.36%, with a slight A + T bias of 52.82%, which was similar to most of the vertebrate mitogenomes. The mitochondrial genome of G. olivaceus had common features regarding gene arrangement and tRNA structures compared with those of other bony fishes.

The Asian Rice Gall Midge (Orseolia oryzae) Mitogenome Has Evolved Novel Gene Boundaries and Tandem Repeats That Distinguish Its Biotypes.

The complete mitochondrial genome of the Asian rice gall midge, Orseolia oryzae (Diptera; Cecidomyiidae) was sequenced, annotated and analysed in the present study. The circular genome is 15,286 bp with 13 protein-coding genes, 22 tRNAs and 2 ribosomal RNA genes, and a 578 bp non-coding control region. All protein coding genes used conventional start codons and terminated with a complete stop codon. The genome presented many unusual features: (1) rearrangement in the order of tRNAs as well as protein coding genes; (2) truncation and unusual secondary structures of tRNAs; (3) presence of two different repeat elements in separate non-coding regions; (4) presence of one pseudo-tRNA gene; (5) inversion of the rRNA genes; (6) higher percentage of non-coding regions when compared with other insect mitogenomes. Rearrangements of the tRNAs and protein coding genes are explained on the basis of tandem duplication and random loss model and why intramitochondrial recombination is a better model for explaining rearrangements in the O. oryzae mitochondrial genome is discussed. Furthermore, we evaluated the number of iterations of the tandem repeat elements found in the mitogenome. This led to the identification of genetic markers capable of differentiating rice gall midge biotypes and the two Orseolia species investigated.

Characterization of the complete mitochondrial genome of the Oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae)

The complete mitochondrial genome (mitogenome) of Mythimna separata (Lepidoptera: Noctuidae) was determined to be 15,329 bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A+T-rich region. The AT skew of this mitogenome was slightly negative and the nucleotide composition was also biased toward A+T nucleotides (81.00%). All PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene, which was initiated by CGA. Five of the 13 PCGs have the incomplete termination codon, T or TA. All the tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The A+T-rich region of the mitogenome was 372 bp in length and consisted of several features common to the Noctuidae. Phylogenetic analysis confirmed the placement of M. separata within the Noctuidae.

DSSR: an integrated software tool for dissecting the spatial structure of RNA.

Insight into the three-dimensional architecture of RNA is essential for understanding its cellular functions. However, even the classic transfer RNA structure contains features that are overlooked by existing bioinformatics tools. Here we present DSSR (Dissecting the Spatial Structure of RNA), an integrated and automated tool for analyzing and annotating RNA tertiary structures. The software identifies canonical and noncanonical base pairs, including those with modified nucleotides, in any tautomeric or protonation state. DSSR detects higher-order coplanar base associations, termed multiplets. It finds arrays of stacked pairs, classifies them by base-pair identity and backbone connectivity, and distinguishes a stem of covalently connected canonical pairs from a helix of stacked pairs of arbitrary type/linkage. DSSR identifies coaxial stacking of multiple stems within a single helix and lists isolated canonical pairs that lie outside of a stem. The program characterizes ‘closed’ loops of various types (hairpin, bulge, internal, and junction loops) and pseudoknots of arbitrary complexity. Notably, DSSR employs isolated pairs and the ends of stems, whether pseudoknotted or not, to define junction loops. This new, inclusive definition provides a novel perspective on the spatial organization of RNA. Tests on all nucleic acid structures in the Protein Data Bank confirm the efficiency and robustness of the software, and applications to representative RNA molecules illustrate its unique features. DSSR and related materials are freely available at http://x3dna.org/.

Effect of Synthetic Polymers on tRNA Nanoparticle Formation

In this review, we have examined the effects of several synthetic nanoparticles such as poly (ethylene glycol) PEG-(PEG-3350, PEG-6000), methoxypoly (ethylene glycol) anthracene (mPEG-anthracene), methoxypoly (ethylene glycol) poly (amidoamine) (mPEG-PAMAM-G3), (mPEG-PAMAM-G4) and poly (amidoamine) (PAMAM-G4) on tRNA structure and dynamics. Atomic force microscopic (AFM) images and spectroscopic data were analysed and the effects of synthetic polymer complexation on tRNA stability, aggregation and particle formation are discussed. Hydrophilic and hydrophobic contacts were dominated in the polymer-tRNA complexation and the overall binding constants showed that the order of binding is PEG-6000>PAMAM-G4>PEG-3350>mPEG-PAMAM-G4>mPEG-PAMAM-G3>mPEG-anthracene. The morphology of polymer-tRNA complexes showed major aggregation and nanoparticle formation of tRNA, in the presence of synthetic nanoparticles.

RNA evolution conjectured from tRNA and riboswitches

The structures of tRNAs and riboswitches comprise distinct domains. A tRNA molecule is L-shaped, and each arm may reflect its evolution. The amino acid-nonspecific minihelix domain may have emerged before the amino acid- specific anticodon-containing domain was acquired. The glycine riboswitch of Bacillus subtilis functions in a glycine- independent manner in the presence of polyethylene glycol or ethylene glycol. The effect is dependent only on the existence of a terminator stem within the expression platform of the riboswitch and is indepen- dent of the aptamer domain. Similar to the hypothesis that explains the evolution of tRNA function, the specificity of riboswitch functional domains may have increased during evolution. Collectively, these views provide new perspectives on the evolution of RNA.

The complete mitochondrial genome of Rondotia menciana (Lepidoptera: Bombycidae).

The mulberry white caterpillar, Rondotia menciana Moore (Lepidoptera: Bombycidae) is a species with closest relationship with Bombyx mori and Bombyx mandarina, and the genetic information of R. menciana is important for understanding the diversity of the Bombycidae. In this study, the mitochondrial genome (mitogenome) of R. menciana was amplified by polymerase chain reaction and sequenced. The mitogenome of R. menciana was determined to be 15,301 bp, including 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, 22 transfer RNA genes, and an AT-rich region. The A+T content (78.87%) was lower than that observed for other Bombycidae insects. All PCGs were initiated by ATN codons and terminated with the canonical stop codons, except for coxII, which was terminated by a single T. All the tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The length of AT-rich region (360 bp) of R. menciana mitogenome is shorter than that of other Bombycidae species. Phylogenetic analysis showed that the R. menciana was clustered on one branch with B. mori and B. mandarina from Bombycidae.

Contribution of tRNA Met core flexibility to aminoacylation

The fidelity of protein synthesis is largely dominated by the correct recognition of transfer RNAs (tRNAs) by their cognate aminoacyl-tRNA synthetases (AARSs). Aminoacylation of each tRNA with its cognate amino acid is necessary to maintain the fidelity of the genetic code. Methionyl-tRNA synthetase (MetRS) aminoacylates both initator and elongator tRNAMet species for protein synthesis; the methionine-specifying CAU anticodon is a key contributor to tRNAMet identify. The communication between tRNAMet and MetRS is not well understood. We hypothesize that the core of tRNAMet is involved in dynamic communication between the tRNA anticodon and acceptor ends, and that such communication contributes to the rearrangement of the tRNA 3′-end to fit into the enzyme active site. Using both experimental and computational approaches, the effects of single nucleotide substitutions in the tRNAMet core and the impact they have on tRNA structure and function will be investigated.

The phenotypic expression of mitochondrial tRNA-mutations can be modulated by either mitochondrial leucyl-tRNA synthetase or the C-terminal domain thereof.

Mutations in mitochondrial (mt) DNA determine important human diseases. The majority of the known pathogenic mutations are located in transfer RNA (tRNA) genes and are responsible for a wide range of currently untreatable disorders. Experimental evidence both in yeast and in human cells has shown that the detrimental effects of mt-tRNA point mutations can be attenuated by increasing the expression of the cognate mt-aminoacyl-tRNA synthetases (aaRSs). In addition, constitutive high levels of isoleucyl-tRNA syntethase have been shown to reduce the penetrance of a homoplasmic mutation in mt-tRNAIle in a small kindred. More recently, we showed that the isolated carboxy-terminal domain of human mt-leucyl tRNA synthetase (LeuRS-Cterm) localizes to mitochondria and ameliorates the energetic defect in transmitochondrial cybrids carrying mutations either in the cognate mt-tRNALeu(UUR) or in the non-cognate mt-tRNAIle gene. Since the mt-LeuRS-Cterm does not possess catalytic activity, its rescuing ability is most likely mediated by a chaperon-like effect, consisting in the stabilization of the tRNA structure altered by the mutation. All together, these observations open potential therapeutic options for mt-tRNA mutations-associated diseases.

The complete mitochondrial genome of the geophilomorph centipede Strigamia maritima.

Strigamia maritima (Myriapoda; Chilopoda) is a species from the soil-living order of geophilomorph centipedes. The Geophilomorpha is the most speciose order of centipedes with over a 1000 species described. They are notable for their large number of appendage bearing segments and are being used as a laboratory model to study the embryological process of segmentation within the myriapods. Using a scaffold derived from the recently published genome of Strigamia maritima that contained multiple mitochondrial protein-coding genes, here we report the complete mitochondrial genome of Strigamia, the first from any geophilomorph centipede. The mitochondrial genome of S. maritima is a circular molecule of 14,938 base pairs, within which we could identify the typical mitochondrial genome complement of 13 protein-coding genes and 2 ribosomal RNA genes. Sequences resembling 16 of the 22 transfer RNA genes typical of metazoan mitochondrial genomes could be identified, many of which have clear deviations from the standard ‘cloverleaf’ secondary structures of tRNA. Phylogenetic trees derived from the concatenated alignment of protein-coding genes of S. maritima and >50 other metazoans were unable to resolve the Myriapoda as monophyletic, but did support a monophyletic group of chilopods: Strigamia was resolved as the sister group of the scolopendromorph Scolopocryptos sp. and these two (Geophilomorpha and Scolopendromorpha), along with the Lithobiomorpha, formed a monophyletic group the Pleurostigmomorpha. Gene order within the S. maritima mitochondrial genome is unique compared to any other arthropod or metazoan mitochondrial genome to which it has been compared. The highly unusual organisation of the mitochondrial genome of Strigamia maritima is in striking contrast with the conservatively evolving nuclear genome: sampling of more members of this order of centipedes will be required to see whether this unusual organization is typical of the Geophilomorpha or results from a more recent reorganisation in the lineage leading to Strigamia.