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At least 109 records · Page 6Linked to original sources
PubMed1981

DNA sequence of the transfer RNA region of bacteriophage T4: implications for transfer RNA synthesis.

Sequences encoding eight tRNAs and two stable RNAs of bacteriophage T4 are grouped together on the T4 genome in two clusters, separated by approximately 500 base pairs. The DNA sequence of part of this region was determined. Within each cluster coding sequences are separated by only one or a few base pairs. These findings imply that the RNAs may be processed from a single multimeric transcript, with initial endonucleolytic cleavages generating the previously characterized monomeric and dimeric precursors.

Base Composition↗
PubMed1983

Measurement of suppressor transfer RNA activity.

Transfer RNA (tRNA) suppression of nonsense mutations in prokaryotic systems has been widely used to study the structure and function of different prokaryotic genes. Through genetic engineering techniques, it is now possible to introduce suppressor (Su+) tRNA molecules into mammalian cells. A quantitative assay of the suppressor tRNA activity in these mammalian cells is described; it is based on the amount of tRNA-mediated readthrough of a terminating codon in the influenza virus NS1 gene after the cells are infected with virus. Suppressor activity in L cells continuously expressing Su+ (tRNAtyr) was 3.5 percent and that in CV-1 cells infected with an SV40- Su+ (tRNAtyr) recombinant was 22.5 percent.

Animals↗
PubMed1988

Evidence for interaction of an aminoacyl transfer RNA synthetase with a region important for the identity of its cognate transfer RNA.

Recent experiments showed that a single base pair (G3:U70) in the amino acid acceptor helix is a major determinant for the identity of Escherichia coli alanine transfer RNA. Experiments reported here show that bound alanine tRNA synthetase protects (from ribonuclease attack) seven consecutive phosphodiester linkages on the 3'-side of the acceptor-T psi C helix (phosphates 65-71) and a few additional sites that are in scattered locations. There is no evidence for interaction of the enzyme with the anticodon, a sequence which can be varied without effect on recognition by alanine tRNA synthetase.

Amino Acyl-tRNA Synthetases↗
PubMed1977

Interrelation between transfer RNA and amino-acid-activating sites of methionyl transfer RNA synthetase from Escherichia coli.

Binding of tRNA(Met/f) to the monomeric trypsin-modified methionyl-tRNA synthetase turns off the methionine-dependent isotopic ATP--PPi exchange. In the case of the dimeric native methionyltRNA synthetase, one anticooperatively bound tRNA(Met/f) inhibits the exchange by only 50%. These behaviours of tRNA do not require the integrity of the 3'-terminal adenosine. Esterification by methionine of the 3' end of tRNA reinforces the affinity of tRNA(Met/f)for the enzymes. In the case of the native enzyme, due to this effect, a second binding mode for methionyl-tRNA may be demonstrated through the isotopic exchange. This additional binding of tRNA corresponds to the expression of the anticooperatively blocked tRNA binding site. Methionine reverses competitively the reinforcing effect of the esterified methionyl moiety on tRNA binding. It is concluded that after esterification of tRNA, the aminoacyl residue still binds the enzyme, probably within the methionine activating site. The latter behaviour may account for the observation that excess methionine accelerates the aminoacylation turnover rate of tRNA(Met/f).

Adenosine Triphosphate↗
PubMed1975

Aminoacyl transfer RNA formation. V. Effect of ethylenediaminetetraacetate on isoleucyl transfer RNA formation stimulated by either spermine or Mg2+.

EDTA inhibited isoleucyl tRNA formation stimulated by spermine in Escherichia coli. It was found that the inhibition by EDTA was not due to contamination of the constituents of the reaction mixture with Mg2+ or to inhibition of the binding of spermine to tRNA by EDTA, but to the interaction of EDTA with isoleucyl-tRNA synthetase. These data suggest the isoleucyl-tRNA synthetase of E. coli contains some metal ion, which is necessary for the enzyme to catalyze the reaction.

Amino Acyl-tRNA Synthetases↗
PubMed2003

Crystal structure of the transfer-RNA domain of transfer-messenger RNA in complex with SmpB.

Accurate translation of genetic information into protein sequence depends on complete messenger RNA molecules. Truncated mRNAs cause synthesis of defective proteins, and arrest ribosomes at the end of their incomplete message. In bacteria, a hybrid RNA molecule that combines the functions of both transfer and messenger RNAs (called tmRNA) rescues stalled ribosomes, and targets aberrant, partially synthesized, proteins for proteolytic degradation. Here we report the 3.2-A-resolution structure of the tRNA-like domain of tmRNA (tmRNA(Delta)) in complex with small protein B (SmpB), a protein essential for biological functions of tmRNA. We find that the flexible RNA molecule adopts an open L-shaped conformation and SmpB binds to its elbow region, stabilizing the single-stranded D-loop in an extended conformation. The most striking feature of the structure of tmRNA(Delta) is a 90 degrees rotation of the TPsiC-arm around the helical axis. Owing to this unusual conformation, the SmpB-tmRNA(Delta) complex positioned into the A-site of the ribosome orients SmpB towards the small ribosomal subunit, and directs tmRNA towards the elongation-factor binding region of the ribosome. On the basis of this structure, we propose a model for the binding of tmRNA on the ribosome.

Bacterial Proteins↗
PubMed1975

Interaction of normal and tumor transfer RNA methyltransferases with ethionine-induced methyl-deficient rat liver transfer RNA.

The tRNA methyltransferases from normal rat liver and Novikoff hepatoma have been compared with respect to their base specificity, capacity to methylate, and reaction kinetics, using mixed Escherichia coli B transfer RNA (tRNA) and ethionine-induced partially methyl-deficient rat liver tRNA. The pattern of base methylation of the two substrates is different with the use of enzymes from either source. In particular, N1-methylguanine methylation is much greater in the methyl-deficient rat liver tRNA. The enzymes from the two sources also show differences in specificity of base methylation in either substrate, particularly in the percentage of N2-methylguanine synthesized. The Novikoff hepatoma enzymes have a greater capacity for methylation with either type of tRNA than do rat liver enzymes. The methyl-deficient rat liver tRNA is a poorer substrate for the enzymes from both sources than is E. coli B tRNA in terms of rate of methylation as well as total acceptance of methyl groups. The affinity constants are somewhat higher for the methyl-deficient rat liver tRNA than for E. coli B tRNA. The Novikoff hepatoma enzymes, in general, have larger affinity constants than the rat liver enzymes. Maximal velocities for the various base-specific enzymes are lower with the methyl-deficient rat liver tRNA, with the exception of the 1-methylguanine specific enzymes. These enzymes from either rat liver or Novikoff hepatoma exhibit approximately a 2.5-fold greater maximal velocity with methyl-deficient rat liver tRNA.

Animals↗
PubMed1975

A novel function of Escherichia coli transfer RNA nucleotidyltransferase. Biosynthesis of the C-C-A sequence in a phage T4 transfer RNA precursor.

The biosynthesis of the phage T4-coded proline and serine transfer RNA species proceeds through a precursor RNA containing both tRNA sequences. Neither tRNA sequence in the precursor RNA contains the 3'-terminal C-C-A common to all mature tRNAs. Seidman and McClain ((1975) Proc. Natl. Acad. Sci. U. S. A. 72, 1491-1495) have proposed that the C-C-A sequence is added to serine tRNA while it is still part of the large precursor RNA. In the present work, I show that, in vitro, a purified preparation of Escherichia coli tRNA nucleotidyltransferase (EC 2.7.7.25) accurately synthesized 3'-terminal C-C-A in the serine tRNA portion of the precursor RNA. This result establishes a role of tRNA nucleotidyltransferase in the biosynthesis of the phage T4 serine tRNA. The finding that tRNA nucleotidyltransferase utilizes the large precursor RNA as a substrate represents a novel function of the enzyme.

Adenine Nucleotides↗