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Abstract
tRNAs are widely believed to segregate into two classes, I and II. Computational analysis of eukaryotic tRNA entries in Genomic tRNA Database, however, leads to new, albeit paradoxical, presence of more than a thousand class-I tRNAs with uncharacteristic long variable arms (V-arms), like in class-II. Out of 62,202 tRNAs from 69 eukaryotes, as many as 1431 class-I tRNAs have these novel extended V-arms, and we refer to them as paradoxical tRNAs (pxtRNAs). A great majority of these 1431 pxtRNA genes are located in intergenic regions, about 18% embedded in introns of genes or ESTs, and just one in 3'UTR. A check on the conservations of 2D and 3D base pairs for each position of these pxtRNAs reveals a few variations, but they seem to have almost all the known features (already known identity and conserved elements of tRNA). Analyses of the A-Box and B-Box of these pxtRNA genes in eukaryotes display salient deviations from the previously annotated conserved features of the standard promoters, whereas the transcription termination signals are just canonical and non-canonical runs of thymidine, similar to the ones in standard tRNA genes. There is just one such pxtRNA(ProAGG) gene in the entire human genome, and the availability of data allows epigenetic analysis of this human pxtRNA(ProAGG) in three different cell lines, H1 hESC, K562, and NHEK, to assess the level of its expression. Histone acetylation and methylation of this lone pxtRNA(ProAGG) gene in human differ from that of the nine standard human tRNA(ProAGG) genes. The V-arm nucleotide sequences and their secondary structures in pxtRNA differ from that of class-II tRNA. Considering these differences, hypotheses of alternative splicing, non-canonical intron and gene transfer are examined to partially improve the Cove scores of these pxtRNAs and to critically question their antecedence and novelty.
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Affiliation(s)
- Sanga Mitra
- a Computational Biology Group , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
| | - Arpa Samadder
- a Computational Biology Group , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
| | - Pijush Das
- b Cancer Biology & Inflammatory Disorder Division , Indian Institute of Chemical Biology , Kolkata , India
| | - Smarajit Das
- c Department of Medical Biochemistry and Cell Biology , Institute of Biomedicine, University of Gothenburg , Gothenburg , Sweden
| | - Jayprokas Chakrabarti
- a Computational Biology Group , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India.,d Gyanxet, BF 286 Salt Lake, Kolkata , India
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Watanabe YI, Suematsu T, Ohtsuki T. Losing the stem-loop structure from metazoan mitochondrial tRNAs and co-evolution of interacting factors. Front Genet 2014; 5:109. [PMID: 24822055 PMCID: PMC4013460 DOI: 10.3389/fgene.2014.00109] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/12/2014] [Indexed: 11/16/2022] Open
Abstract
Conventional tRNAs have highly conserved sequences, four-armed cloverleaf secondary structures, and L-shaped tertiary structures. However, metazoan mitochondrial tRNAs contain several exceptional structures. Almost all tRNAsSer for AGY/N codons lack the D-arm. Furthermore, in some nematodes, no four-armed cloverleaf-type tRNAs are present: two tRNAsSer without the D-arm and 20 tRNAs without the T-arm are found. Previously, we showed that in nematode mitochondria, an extra elongation factor Tu (EF-Tu) has evolved to support interaction with tRNAs lacking the T-arm, which interact with C-terminal domain 3 in conventional EF-Tu. Recent mitochondrial genome analyses have suggested that in metazoan lineages other than nematodes, tRNAs without the T-arm are present. Furthermore, even more simplified tRNAs are predicted in some lineages. In this review, we discuss mitochondrial tRNAs with divergent structures, as well as protein factors, including EF-Tu, that support the function of truncated metazoan mitochondrial tRNAs.
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Affiliation(s)
- Yoh-Ichi Watanabe
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
| | - Takuma Suematsu
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
| | - Takashi Ohtsuki
- Department of Biotechnology, Okayama University Okayama, Japan
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Idiosyncrasies in decoding mitochondrial genomes. Biochimie 2014; 100:95-106. [PMID: 24440477 DOI: 10.1016/j.biochi.2014.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Accepted: 01/06/2014] [Indexed: 11/24/2022]
Abstract
Mitochondria originate from the α-proteobacterial domain of life. Since this unique event occurred, mitochondrial genomes of protozoans, fungi, plants and metazoans have highly derived and diverged away from the common ancestral DNA. These resulting genomes highly differ from one another, but all present-day mitochondrial DNAs have a very reduced coding capacity. Strikingly however, ATP production coupled to electron transport and translation of mitochondrial proteins are the two common functions retained in all mitochondrial DNAs. Paradoxically, most components essential for these two functions are now expressed from nuclear genes. Understanding how mitochondrial translation evolved in various eukaryotic models is essential to acquire new knowledge of mitochondrial genome expression. In this review, we provide a thorough analysis of the idiosyncrasies of mitochondrial translation as they occur between organisms. We address this by looking at mitochondrial codon usage and tRNA content. Then, we look at the aminoacyl-tRNA-forming enzymes in terms of peculiarities, dual origin, and alternate function(s). Finally we give examples of the atypical structural properties of mitochondrial tRNAs found in some organisms and the resulting adaptive tRNA-protein partnership.
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Tehrani ZA, Abedin A, Shakourian-Fard M, Fattahi A. What roles do boron substitutions play in structural, tautomeric, base pairing and electronic properties of uracil? NBO & AIM analysis. J PHYS ORG CHEM 2012. [DOI: 10.1002/poc.2918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Azar Abedin
- Department of Chemistry; Sharif University of Technology; Tehran Iran
| | | | - Alireza Fattahi
- Department of Chemistry; Sharif University of Technology; Tehran Iran
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Wenska G, Taras-Goślińska K, Łukaszewicz A, Burdziński G, Koput J, Maciejewski A. Mechanism and dynamics of intramolecular triplet state decay of 1-propyl-4-thiouracil and its α-methyl-substituted derivatives studied in perfluoro-1,3-dimethylcyclohexane. Photochem Photobiol Sci 2011; 10:1294-302. [PMID: 21594285 DOI: 10.1039/c1pp05034f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The absorption, phosphorescence and phosphorescence excitation spectra, phosphorescence quantum yields, and T(1) excited state lifetimes of four 4-thiouracil derivatives were measured for the first time in chemically inert and very weakly interacting perfluoro-1,3-dimethylcyclohexane at room temperature. The set of the 4-thiouracil derivatives comprises 1-propyl-4-thiouracil (PTU) and the related compounds having a methyl substituent at the position α to the thiocarbonyl group, namely 1-propyl-4-thiothymine (PTT), 1,3-dimethyl-4-thiouracil (DMTU), and 1-methyl-3-trideuteriomethyl-4-thiouracil ([D(3)]DMTU). Quantitative information on the intramolecular decay of the T(1) excited state of the four 4-thiouracil derivatives is presented, and the mechanism and dynamics of this process are discussed. In the absence of self quenching and solvent induced deactivation, the T(1) decay of the four 4-thiouracil derivatives was dominated by intramolecular nonradiative processes (NR). The values of the rate constant k(NR) in DMTU and [D(3)]DMTU are about 4 times larger than that in PTT and about 3 times larger than that in PTU. The reasons for the enhanced nonradiative rate constant in DMTU are discussed. It is concluded that the faster rate of the nonradiative processes in DMTU is related to a larger contribution from mixing of the T(2) (nπ*) state into the lowest energy T(1) (ππ*) state, as compared to the analogous coupling in PTU and PTT. This conclusion is supported by ab initio calculations performed at the EOM-CC2/aug-cc-pVDZ level of theory. The energy spacing between the T(2) (nπ*) and T(1) (ππ*) states is estimated to be about 500, 1100, and 2000 cm(-1) for DMTU, PTU, and PTT, respectively. Among the three compounds in question, the predicted energy spacing is thus the smallest for DMTU.
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Affiliation(s)
- Grazyna Wenska
- Faculty of Chemistry, Adam Mickiewicz University, 60-780, Poznan, Poland.
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Alexander RW, Eargle J, Luthey-Schulten Z. Experimental and computational determination of tRNA dynamics. FEBS Lett 2009; 584:376-86. [PMID: 19932098 DOI: 10.1016/j.febslet.2009.11.061] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 11/14/2009] [Accepted: 11/16/2009] [Indexed: 10/20/2022]
Abstract
As the molecular representation of the genetic code, tRNA plays a central role in the translational machinery where it interacts with several proteins and other RNAs during the course of protein synthesis. These interactions exploit the dynamic flexibility of tRNA. In this minireview, we discuss the effects of modified bases, ions, and proteins on tRNA structure and dynamics and the challenges of observing its motions over the cycle of translation.
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Affiliation(s)
- Rebecca W Alexander
- Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109-7486, United States.
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Qiu Z, Xia Y, Wang H, Diao K. MP2 study on the hydrogen-bonding interactions between 4-thiouracil and four RNA bases. Struct Chem 2009. [DOI: 10.1007/s11224-009-9528-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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The dimeric proto-ribosome: Structural details and possible implications on the origin of life. Int J Mol Sci 2009; 10:2921-2934. [PMID: 19742176 PMCID: PMC2738903 DOI: 10.3390/ijms10072921] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 06/25/2009] [Indexed: 11/16/2022] Open
Abstract
A symmetric pocket-like entity, composed of two L-shaped RNA units, encircles the peptide synthesis site within the contemporary ribosome. This entity was suggested to be the vestige of a dimeric proto-ribosome, which could have formed spontaneously in the prebiotic world, catalyzing non-coded peptide bond formation and elongation. This structural element, beyond offering the initial step in the evolution of translation, is hypothesized here to be linked to the origin of life. By catalyzing the production of random peptide chains, the proto-ribosome could have enabled the formation of primary enzymes, launching a process of co-evolution of the translation apparatus and the proteins, thus presenting an alternative to the RNA world hypothesis.
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Frazer-Abel AA, Hagerman PJ. Core flexibility of a truncated metazoan mitochondrial tRNA. Nucleic Acids Res 2008; 36:5472-81. [PMID: 18718926 PMCID: PMC2553581 DOI: 10.1093/nar/gkn529] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Secondary and tertiary structures of tRNAs are remarkably preserved from bacteria to humans, the notable exception being the mitochondrial (m) tRNAs of metazoans, which often deviate substantially from the canonical cloverleaf (secondary) or ‘L’-shaped (tertiary) structure. Many metazoan mtRNAs lack either the TψC (T) or dihydrouridine (D) loops of the canonical cloverleaf, which are known to confer structural rigidity to the folded structure. Thus, the absence of canonical TψC–D interactions likely results in greater dispersion of anticodon-acceptor interstem angle than for canonical tRNAs. To test this hypothesis, we have assessed the dispersion of the anticodon-acceptor angle for bovine mtRNASer(AGY), which lacks the canonical D arm and is thus incapable of forming stabilizing interarm interactions. Using the method of transient electric birefringence (TEB), and by changing the helical torsion angle between a core mtRNA bend and a second bend of known angle/rigidity, we have demonstrated that the core of mtRNASer(AGY) has substantially greater flexibility than its well-characterized canonical counterpart, yeast cytoplasmic tRNAPhe. These results suggest that increased flexibility, in addition to a more open interstem angle, would allow both noncanonical and canonical mtRNAs to utilize the same protein synthetic apparatus.
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Masta SE, Boore JL. Parallel Evolution of Truncated Transfer RNA Genes in Arachnid Mitochondrial Genomes. Mol Biol Evol 2008; 25:949-59. [DOI: 10.1093/molbev/msn051] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Chimnaronk S, Gravers Jeppesen M, Suzuki T, Nyborg J, Watanabe K. Dual-mode recognition of noncanonical tRNAs(Ser) by seryl-tRNA synthetase in mammalian mitochondria. EMBO J 2005; 24:3369-79. [PMID: 16163389 PMCID: PMC1276171 DOI: 10.1038/sj.emboj.7600811] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Accepted: 08/22/2005] [Indexed: 11/09/2022] Open
Abstract
The secondary structures of metazoan mitochondrial (mt) tRNAs(Ser) deviate markedly from the paradigm of the canonical cloverleaf structure; particularly, tRNA(Ser)(GCU) corresponding to the AGY codon (Y=U and C) is highly truncated and intrinsically missing the entire dihydrouridine arm. None of the mt serine isoacceptors possesses the elongated variable arm, which is the universal landmark for recognition by seryl-tRNA synthetase (SerRS). Here, we report the crystal structure of mammalian mt SerRS from Bos taurus in complex with seryl adenylate at an atomic resolution of 1.65 A. Coupling structural information with a tRNA-docking model and the mutagenesis studies, we have unraveled the key elements that establish tRNA binding specificity, differ from all other known bacterial and eukaryotic systems, are the characteristic extensions in both extremities, as well as a few basic residues residing in the amino-terminal helical arm of mt SerRS. Our data further uncover an unprecedented mechanism of a dual-mode recognition employed to discriminate two distinct 'bizarre' mt tRNAs(Ser) by alternative combination of interaction sites.
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Affiliation(s)
- Sarin Chimnaronk
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan
| | | | - Tsutomu Suzuki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan
| | - Jens Nyborg
- Department of Molecular Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Kimitsuna Watanabe
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan
- Present address: Biological Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-42 Aomi, Koto-ku, Tokyo 135-0064, Japan
- Biological Information Research Center, National Institute of Advanced Industrial Science & Technology (AIST), 2-42 Aomi, Koto-ku, Tokyo 135-0064, Japan. Tel.:+81 3 3599 8106; Fax: +81 3 5530 2064; E-mail:
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