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At least 163 records · Page 9Linked to original sources
PubMed1977

Stringent regulation of the synthesis of a transfer ribonucleic acid biosynthetic enzyme: transfer ribonucleic acid(m5U)methyltransferase from Escherichia coli.

This paper describes the regulation of a transfer ribonucleic acid (tRNA) biosynthetic enzyme, the tRNA(m5U)methyltransferase (EC 2.1.1.35). This enzyme catalyzes the formation of 5-methyluridine (m5U, ribothymidine) in all tRNA chains of Escherichia coli. Partial deprivation of charged tRNAVal can be imposed by shifting strains carrying a temperature-sensitive valyl-tRNA ligase from a permissive to a semipermissive temperature. By using two such strains differing only in the allelic state of the relA gene, it was possible to show the tRNA(m5U)methyltransferase to be stringently regulated. Upon partial deprivation of charged tRNAVal, the differential rate of tRNA(m5U)methyltransferase synthesis was found to decrease in a strain with stringent RNA control (relA+), whereas it increased in the strain carrying the relA allele. This increase of accumulation of tRNA(m5U)methyltransferase activity required protein synthesis. Thus, when tRNA is partially uncharged in the cell, the relA gene product influences the expression of tRNA(m5U)methyltransferase gene.

Bacterial Proteins↗
PubMed1965

Role of aminoacyl-transfer ribonucleic acid in the regulation of ribonucleic acid synthesis in Escherichia coli.

Morris, D. W. (University of California, San Diego), and J. A. DeMoss. Role of aminoacyl-transfer ribonucleic acid in the regulation of ribonucleic acid synthesis in Escherichia coli. J. Bacteriol. 90:1624-1631. 1965.-A leucine auxotroph of Escherichia coli was examined for its rate of ribonucleic acid (RNA) synthesis and the level of charged leucine-, arginine-, and valine-specific transfer RNA (tRNA) during the exponential growth period and when growth was limited by leucine starvation. During the logarithmic growth period, the leucine-specific tRNA was 70% charged, arginine-specific tRNA was 30% charged, and the valine-specific tRNA was 80% charged. When leucine became limiting, RNA synthesis was inhibited and the levels of charged arginine- and valine-specific tRNA remained constant, whereas the level of charged leucine-specific tRNA dropped to 40%. Examination of the leucyl-tRNA during the leucine starvation period showed that this 40% level is maintained by protein turnover. Addition of chloramphenicol or puromycin to a leucine-starved culture derepressed RNA synthesis. In the presence of chloramphenicol, the leucine-specific tRNA was fully charged; however, in the presence of puromycin the amount of charged leucine-specific tRNA remained at the starved level. Therefore, during leucine starvation the level of uncharged leucine-specific tRNA is not invariably correlated with the rate of RNA synthesis. We propose that it is the availability of charged tRNA and not the amount of uncharged tRNA which is the important factor in the amino acid control of RNA synthesis.

Chloramphenicol↗
PubMed1972

Transcription and transport of virus-specific ribonucleic acids in African green monkey kidney cells abortively infected with type 2 adenovirus.

The techniques of deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization and immunological precipitation were used to compare the synthesis of adenovirus-specific macromolecules in African green monkey kidney (AGMK) cells infected with adenovirus, an abortive infection, and coinfected with both adenovirus and simian virus 40 (SV40), which renders the cells permissive for adenovirus replication. When viral protein synthesis was proceeding at its maximum rate, the incorporation of (14)C-amino acids into adenovirus structural proteins was about 90 times greater in the doubly infected cells than in cells infected only with adenovirus. However, the rates of synthesis of virus-specific ribonucleic acid appeared to be comparable in the two infections at all times measured. A time-dependent increase in the rate of RNA synthesis observed late in the abortive infection was dependent upon the prior replication of viral DNA. Moreover, all virus-specific RNA species that are normally made late in a productive adenovirus infection (i.e., the true late and class II early RNA species) were also detected in the abortive infection. Adenovirus-specific RNA was detected by molecular hybridization in both the cytoplasm and nuclei of abortively infected cells. Comparable amounts of viral RNA were found in the cytoplasmic fractions of AGMK cells infected either with adenovirus or with both adenovirus and SV40. The results of hybridization-inhibition experiments clearly showed that there was a class of virus-specific RNA molecules, representing about 30% of the total, in the nucleus that was not transported to the cytoplasm. This class of RNA was also identified in similar amounts in productively infected human KB cells. The difference in the abilities of cytoplasmic and nuclear RNA to inhibit the hybridization of virus-specific RNA from whole cells was shown not to be due to a difference in the molecular size of the RNA species from the two cell fractions or to the specific loss of a cytoplasmic species during RNA extraction procedures.

Adenoviridae↗
PubMed1967

Denaturation and renaturation of viral ribonucleic acid. I. Annealing R17 ribonucleic acid with denatured replicative form or with denatured replicative intermediate.

Purified replicative form (RF) and replicative intermediate (RI) prepared from Escherichia coli infected with R17 were denatured in 0.15 m NaCl, 0.015 m sodium citrate containing 65% dimethylsulfoxide. Denaturation of RF or RI was demonstrated spectrophotometrically, chromatographically, and by sedimentation analysis. Denatured RF or RI was annealed by carefully decreasing the temperature from 62 to 20 C. Annealing was accompanied by a decreased absorbance at 260 mmu. The decrease in absorbance during annealing appeared to be dependent upon the rate of cooling and the concentration of ribonucleic acid (RNA). Denatured RF or RI was annealed with R17 RNA which was labeled with (3)H-uridine. The annealed product was 73 to 82% resistant to 0.1 mug/ml of ribonuclease. Annealing R17 RNA with either denatured RF or RI resulted in the formation of a ribonuclease-resistant product with a sedimentation profile resembling that of native RI. Melting the annealed products in 85.7% dimethyl sulfoxide produced 27S single-stranded R17 RNA and a heterogeneous population of more slowly sedimenting RNA.

Centrifugation, Density Gradient↗
PubMed1980

Use of oligodeoxynucleotide primers to determine poly(adenylic acid) adjacent sequences in messenger ribonucleic acid. 3'-Terminal noncoding sequence of bovine growth hormone messenger ribonucleic acid.

Twelve synthetic oligodeoxynucleotide primers of the general sequence d(pT8-N-N') were tested in a reverse transcriptase reaction for specific initiation of complementary deoxyribonucleic acid (cDNA) synthesis at the poly(adenylic acid) junction of a messenger ribonucleic acid (mRNA) template. Only the sequence d(pT8-G-C) functioned as a specific primer of cDNA synthesis with an enriched fraction of bovine growth hormone mRNA from the anterior pituitary gland and produced unique fragments in a dideoxy sequencing reaction. The nucleotide sequence obtained by this method extended into the protein coding region of bovine growth hormone mRNA and was confirmed by chemical sequencing of the cDNA initiated with [5'-32P]d(pT8-G-C). The 3'-untranslated region of bovine growth hormone mRNA is 104 nucleotides in length and contains regions of significant homology with both rat and human growth hormone mRNAs, including the region surrounding the common AAUAAA hexanucleotide. The method presented here for selection of the d(pT8-N-N') primer complementary to the poly(A) junction of mRNA is of general applicability for nucleotide sequence analysis of partially purified mRNAs.

Animals↗
PubMed1970

Foot-and-mouth disease virus-induced alterations of baby hamster kidney cell macromolecular biosynthesis: inhibition of ribonucleic acid methylation and stimulation of ribonucleic acid synthesis.

The kinetics of ribonucleic acid (RNA) and protein synthesis and RNA methylation were examined after foot-and-mouth disease virus (FMDV) infection of baby hamster kidney cells. The synthesis of RNA extracted from the whole cells was stimulated two- to threefold above the control level of synthesis. This increased rate was attributed to viral RNA synthesis. The inhibition of host RNA methylation was concomitant with but more pronounced than protein synthesis inhibition. The methylation of transfer RNA was initially inhibited by virus infection, but rose to within 70 to 80% of the control level just prior to the production of maximal amounts of virus-specific RNA polymerase. Cycloheximide studies showed that rapid cessation of protein synthesis did not result in the immediate cessation of RNA methylation. A comparison between the kinetics of inhibition of these processes by cycloheximide and FMDV infection suggests that FMDV selectively inhibits RNA methylation.

Animals↗