• Title/Summary/Keyword: anticodon

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Studies on the Oranization and Expression of tRNA Genes in Aspergillus nidulans (V) The Molecular Structure of $tRNA^{Arg}$ in Aspergillus nidulans (Aspergillus nidulans의 tRNA유전자의 구조와 발현에 관한 연구 V Aspergillus nidulansd의 $tRNA^{Arg}$ 분자구조)

  • 이병재;강현삼
    • Korean Journal of Microbiology
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    • v.24 no.2
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    • pp.79-85
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    • 1986
  • We have determined the sequence of $tRNA^{Arg}$ of A. nidulans partially by enzymatic rapid RNA sequencing technique. The sequence was 5'GGCCGGCUGGCCCAAXUGGCAAGGXUCUGAXUACGAAXCAGGAGAUUGCACXXXXXGAGCXXUXXGUCGGUCACCA3' The cloverleaf structure was made from above data. As a result, the anticodon sequence was identified as ACG. This result was confirmed with charging test. The complete sequence was proposed by supplementing the DNA sequence to and by assigning the position of minor bases to this RNA sequence.

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Transfer RNA Acceptor Stem Determinants for Specific Aminoacylation by Class II Aminoacyl-tRNA Synthetases

  • Musier, Karin
    • BMB Reports
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    • v.31 no.6
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    • pp.525-535
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    • 1998
  • A critical step in the faithful translation of genetic information is specific tRNA recognition by aminoacyl-tRNA synthetases. These enzymes catalyze the covalent attachment of particular amino acids to the terminal adenosine of cognate tRNA substrates. In general, there is one synthetase for each of the twenty amino acids and each enzyme must discriminate against all of the cellular tRNAs that are specific for the nineteen noncognate amino acids. Primary sequence information combined with structural data have resulted in the division of the twenty synthetases into two classes. In recent years, several high-resolution co-crystal structures along with biochemical data have led to an increased understanding of tRNA recognition by synthetases of both classes. The anticodon sequence and the amino acid acceptor stem are the most common locations for critical recognition elements. This review will focus on acceptor stem discrimination by class II synthetases. In particular, the results of in vitro aminoacylation assays and site-directed and atomic group mutagenesis studies will be discussed. These studies have revealed that even subtle atomic determinants can provide signals for specific tRNA aminoacylation.

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Evidence on the Presence of $tRNA^{fMet}$ Group I Intron in the Marine Cyanobacterium Synechococcus elongatus

  • Muralitharan, Gangatharan;Thajuddin, Nooruddin
    • Journal of Microbiology and Biotechnology
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    • v.18 no.1
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    • pp.23-27
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    • 2008
  • Self-splicing group I introns in tRNA anticodon loops have been found in diverse groups of bacteria. In this work, we identified $tRNA^{fMet}$ group I introns in six strains of marine Synechococcus elongatus. Introns with sizes around 280 bp were consistently obtained in all the strains tested. In a phylogenetic analysis using the nucleotide sequence determined in this study with other cyanobacterial $tRNA^{fMet}$ and $tRNA^{Leu}$ intron sequences, the Synechococcus sequence was grouped together with the sequences from other unicellular cyanobacterial strains. Interestingly, the phylogenetic tree inferred from the intronic sequences clearly separates the different tRNA introns, suggesting that each family has its own evolutionary history.

Bacterial Logic Devices Reveal Unexpected Behavior of Frameshift Suppressor tRNAs

  • Sawyer, Eric M.;Barta, Cody;Clemente, Romina;Conn, Michel;Davis, Clif;Doyle, Catherine;Gearing, Mary;Ho-Shing, Olivia;Mooney, Alyndria;Morton, Jerrad;Punjabi, Shamita;Schnoor, Ashley;Sun, Siya;Suresh, Shashank;Szczepanik, Bryce;Taylor, D. Leland;Temmink, Annie;Vernon, William;Campbell, A. Malcolm;Heyer, Laurie J.;Poet, Jeffrey L.;Eckdahl, Todd T.
    • Interdisciplinary Bio Central
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    • v.4 no.3
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    • pp.10.1-10.12
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    • 2012
  • Introduction: We investigated frameshift suppressor tRNAs previously reported to use five-base anticodon-codon interactions in order to provide a collection of frameshift suppressor tRNAs to the synthetic biology community and to develop modular frameshift suppressor logic devices for use in synthetic biology applications. Results and Discussion: We adapted eleven previously described frameshift suppressor tRNAs to the BioBrick cloning format, and built three genetic logic circuits to detect frameshift suppression. The three circuits employed three different mechanisms: direct frameshift suppression of reporter gene mutations, frameshift suppression leading to positive feedback via quorum sensing, and enzymatic amplification of frameshift suppression signals. In the course of testing frameshift suppressor logic, we uncovered unexpected behavior in the frameshift suppressor tRNAs. The results led us to posit a four-base binding hypothesis for the frameshift suppressor tRNA interactions with mRNA as an alternative to the published five-base binding model. Conclusion and Prospects: The published five-base anticodon/codon rule explained only 17 of the 58 frameshift suppression experiments we conducted. Our deduced four-base binding rule successfully explained 56 out of our 58 frameshift suppression results. In the process of applying biological knowledge about frameshift suppressor tRNAs to the engineering application of frameshift suppressor logic, we discovered new biological knowledge. This knowledge leads to a redesign of the original engineering application and encourages new ones. Our study reinforces the concept that synthetic biology is often a winding path from science to engineering and back again; scientific investigations spark engineering applications, the implementation of which suggests new scientific investigations.

Isolation of New Self-Cleaving Ribozymes with in vitro Selection

  • Cho, Bong-Rae;Lee, Young-Hoon
    • Bulletin of the Korean Chemical Society
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    • v.26 no.12
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    • pp.2033-2037
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    • 2005
  • In vitro selection was used to isolate $Mg^{2+}$-dependent self-cleaving ribozymes with cis-cleavage activity from a pre-tRNA library having 40-mer random sequences attached to 5'-end of E. coli $tRNA^{Phe}$. After 8 rounds of SELEX (Systematic Evolution of Ligands by Exponential Enrichment), RNA molecules which can self-cleave at the high concentration of $Mg^{2+}$ were isolated. The selected ribozymes can carry out the self-cleavage reaction in the presence of 100 mM $Mg^{2+}$ but not in 10 mM $Mg^{2+}$. The cleavage sites of the ribozymes are located at +3 and +4 of $tRNA^{Phe}$, compared with +1 position of 5'-end cleavage site of pre-tRNA by RNase P. New RNA constructs deprived of its D stem-loop, anticodon stem-loop, variable loop and T stem-loop, respectively showed the cleavage specificity identical to a ribozyme having the intact tRNA structure. Also, the new ribozyme fused with both a ribozyme and $tRNA^{Leu}$ showed the cleavage activities at the various sites within its sequences, different from two sites of position +3 and +4 observed in the ribozyme with $tRNA^{Phe}$. Our results suggest that the selected ribozyme is not structural-specific for tRNA.

CRYSTAL STRUCTURE OF tRNA ($m^1$ G37) METHYLTRANSFERASE

  • Ahn, Hyung-Jun;Lee, Byung-Ill;Yoon, Hye-Jin;Yang, Jin-Kuk;Suh, Se-Won
    • Proceedings of the Korea Crystallographic Association Conference
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    • 2003.05a
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    • pp.17-17
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    • 2003
  • tRNA (m¹ G37) methyltransferase (TrmD) catalyze s the trans for of a methyl group from S-adenosyl-L-methionine (AdoMet) to G/sup 37/ within a subset of bacterial tRNA species, which have a residue G at 36th position. The modified guanosine is adjacent to and 3' of the anticodon and is essential for the maintenance of the correct reading frame during translation. We have determined the first crystal structure of TrmD from Haemophilus influenzae, as a binary complex with either AdoMet or S-adenosyl-L-homocysteine (AdoHcy), as a ternary complex with AdoHcy/phosphate, and as an apo form. The structure indicates that TrmD functions as a dimer (Figure 1). It also suggests the binding mode of G/sup 36/G/sup 37/ in the active site of TrmD and catalytic mechanism. The N-terminal domain has a trefoil knot, in which AdoMet or AdoHcy is bound in a novel, bent conformation. The C-terminal domain shows a structural similarity to DNA binding domain of trp or tot repressor. We propose a plausible model for the TrmD₂-tRNA₂ complex, which provides insights into recognition of the general tRNA structure by TrmD (Figure 2).

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Construction and characterization of heterozygous diploid Escherichia coli (2배체 대장균의 제조와 그 특성)

  • Jung, Hyeim;Lim, Dongbin
    • Korean Journal of Microbiology
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    • v.52 no.4
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    • pp.406-414
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    • 2016
  • Among 6 leu codons, CUG is the most frequently used codon in E. coli. It is recognized by leu-tRNA(CAG) encoded by four genes scattered on two chromosomal loci (leuT and leuPQV ). In the process of constructing a strain with no functional leu-tRNA (CAG) gene on chromosome, we made two mutant strains separately, one on leuPQV locus (${\Delta}leuPQV$), and the other on leuT locus [$leuT^*$(GAG)], where the anticodon of leuT was changed from CAG to GAG, thereby altering its recognition codon from CUG to CUC. We attempted to combine these two mutations by transduction using $leuT^*$(GAG) strain as a donor and ${\Delta}leuPQV$ strain as a recipient. Large and small colonies appeared from this transduction. From PCR and DNA sequencing, large colony was confirmed to be the reciprocal recombinant as expected, but the small colonies contained both mutant $leuT^*$(GAG) and wild type leuT (CAG) genes in the cell. This heterozygous diploid strain did not show any unusual morphology under microscopic observation, but, interestingly, it showed a linear growth curve in rich medium with much slower growth rate than wild type cell. It always formed homogenous small colonies in the selection medium, but, when there was no selection, it readily segregated into $leuT^*$(GAG) and leuT (CAG). From these observations, we suggested that the strain with both $leuT^*$(GAG) and leuT (CAG) genes was not a partial diploid (merodiploid), but a full diploid cell having two different chromosomes. We proposed a model explaining how such a heterozygous diploid cell was formed and how and why its growth showed a linear growth curve.