RNA sequences in ribonucleoprotein fragments of the complex formed from ribosomal 23-S RNA and ribosomal protein L24 of Escherichia coli.

Upon digestion of the complex formed from the 23-S ribosomal RNA and the 50-S ribosomal protein L24 of Escherichia coli, two fragments resistant to ribonuclease were recovered; these fragments contained RNA sections belonging to the 480 nucleotides at the 5' end of 23-S RNA. By determining the sequence of 70% of this latter region we were able to localise the sections which, in the presence of the protein, are resistant to ribonuclease. Our results suggest that the region encompassing the 480 nucleotides starting at the 9th nucleotide from the 5' end of 23-S RNA has a compact tertiary structure, which is stabilised by protein L24.

Non-equivalence of the sites of yeast phenylalanyl-tRNA synthetase during catalysis.

Yeast phenylalanyl-tRNA synthetase, an enzyme with an alpha2beta2 structure, has two active sites for phenylalanine, tRNAphe, phenylalanyladenylate and phenylalanyl-tRNAphe. Determination of phenylalanine binding properties to the free enzyme by equilibrium dialysis shows that only one mole of amino acid binds per mole of enzyme, i.e.

The yeast aminoacyl-tRNA synthetases. Methodology for their complete or partial purification and comparison of their relative activities under various extraction conditions.

Several fractionation steps are described which can be applied to the partial purification of the 20 aminoacyl-tRNA synthetases from commercial baker's yeast. Comparative experiments performed in the presence or absence of protease inhibitors revealed that some enzymes prepared in the presence of the inhibitor exhibit much higher specific activities than the proteins extracted in the absence of the inhibitor. The methodology reported can be used for the simultaneous preparation of several pure aminoacyl-tRNA synthetases.

The binding site of protein L1 ON 23-S ribosomal RNA of Escherichia coli. 2. Identification of the rna region contained in the L1 ribonucleoproteins and determination of the order of the RNA subfragments within this region.

Ribonucleoproteins were obtained by T1 ribonuclease digestion of reconstitued complexes of ribosomal protein L1 AND 23-S RNA from Escherichia coli. The RNA region of the main ribonucleoprotein 2 was totally digested with T1 ribonuclease. The oligonucleotide products were characterised and they showed that this region comprises 148 nucleotides located between the 550th and 1000th necleotides from the 3' end of the 23-S RNA.

Interpretation of tRNA-mischarging kinetics.

Incorrect tRNA aminoacylation reactions are characterized by very slow reaction rates and by the fact that in most cases they are incomplete. In a previous study some of us explained the incompleteness of the correct aminoacylation reactions of tRNA, which can be encountered under certain experimental conditions (for instance low enzyme concentration or high ionic strength) by an equilibrium between the aminoacylation and the deacylation reactions [J. Bonnet and J.

Yellowstone: seismic evidence for a chemical mantle plume.

Arrivals of P waves from a recent event at the Nevada Test Site, recorded at a distance of 15.3 degrees , passed beneath the Yellowstone caldera at depths of 200 and 400 kilometers. The travel time anomalies are modeled by a vertical cylindrical structure with a high-velocity core and a low-velocity collar as compared with the more normal mantle.

Messenger RNA translation in the presence of homologous and heterologous tRNA.

The effect of tRNA distribution in the cell on the rate of specific protein synthesis has been investigated. A tRNA-dependent cell-free protein-synthesizing system derived from Krebs-II ascites cells has been worked out. In this system it is possible to synthesize specific proteins (egg-white proteins or globin) by the translation of oviduct or reticulocyte messenger RNA in the presence of tRNA from homologous or heterologous tissues.

Inhibition of viral multiplication by homologous methylated ribonucleic acids. V. Inhibition of myxoviruses in mouse.

Mice respond to intravenous injection of homologous methylated RNA by the production of a circulating interferon-like substance. The treatment with modified RNA induces a significant protection against viral infection. This effect is optimum when the treatment occurs a few hours before viral infection.

Extensions of the known sequences at the 3' and 5' ends of 23S ribosomal RNA from Escherichia coli, possible base pairing between these 23S RNA regions and 16S ribosomal RNA.

Extensions of the known sequences at both 3' and 5' ends of 23S ribosomal RNA are presented: The 5' terminal is pG-G-U-U-A-A-G-Cp or pG-G-U...

Enzymic synthesis of lignin precursors. Purification and properties of a cinnamoyl-CoA: NADPH reductase from cell suspension cultures of soybean (Glycinemax).

A cinnamoyl-coenzyme A reductase catalyzing the NADPH-dependent reduction of substituted cinnamoyl-CoA thiol esters to the corresponding cinnamaldehydes was isolated from cell suspension cultures of soybean (Glycine max L. var. Mandarin).

Host-Pathogen Interactions: XII. Response of Suspension-cultured Soybean Cells to the Elicitor Isolated from Phytophthora megasperma var. sojae, a Fungal Pathogen of Soybeans.

The glucan elicitor isolated from the mycelial walls of Phytophthora megasperma var. sojae, the fungus which causes stem and root rot in soybeans, stimulates the activity of phenylalanine ammonia-lyase and the accumulation of glyceollin in suspension-cultured soybean cells. Nigeran, a commercially available fungal wall glucan, was the only other compound tested which has any activity in this system.

Host-Pathogen Interactions: XI. Composition and Structure of Wall-released Elicitor Fractions.

The structures of the four wall-released elicitor fractions isolated from the Phytophthora megasperma var. sojae mycelial walls have been examined. The results demonstrate that fraction I is primarily composed of a branched beta-1,3-glucan, similar in structure to the extracellular elicitors described previously (Ayers, A.

Host-Pathogen Interactions: X. Fractionation and Biological Activity of an Elicitor Isolated from the Mycelial Walls of Phytophthora megasperma var. sojae.

An elicitor of phytoalexin production in soybean (Glycine max L.) tissues was isolated from purified Phytophthora megasperma var. sojae mycelial walls by a heat treatment similar to that used to solubilize the surface antigens from the cell walls of Saccharomyces cerevisiae.

Host-Pathogen Interactions: IX. Quantitative Assays of Elicitor Activity and Characterization of the Elicitor Present in the Extracellular Medium of Cultures of Phytophthora megasperma var. sojae.

Resistance of soybean (Glycine max L.) seedlings to Phytophthora megasperma var. sojae (Pms) is in part due to the accumulation in infected tissue of a compound which is toxic to Pms.