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E Ia Gren

Publications and source records attributed to E Ia Gren.

28 records · Page 2Linked to original sources
PubMedDate not supplied

[MS2 RNA hydrolysis by snake venom phosphodiesterase and template properties of RNA produced by limited exonucleolytic action].

The action of snake venom phosphodiesterase on bacteriophage MS2 RNA under conditions of limited hydrolysis has been studied. The content of 5'-mononucleotides released during hydrolysis does not correspond to the calculated one based on the 3'-terminal nucleotide sequence of MS2 RNA. This finding suggests the occurrence of endonucleolytic splits in MS2 RNA with concomitant exonucleolytic digestion of some newly formed fragments. A high molecular weight RNA fraction, comprising unfragmented MS2 RNA with about 5-63'-terminal nucleotides removed is separated by sucrose gradient centrifugation and shown not to differ from the native MS2 RNA in its template function in a cell-free protein synthesizing system. It is demonstrated that template activity, polarity of translation, and nascent peptide chain termination on the MS2 replicase cistron are not affected by the removal of 3'terminal nucleotides of MS2 RNA. Consequently, these nucleotides are unessential in translation of native MS2 RNA.

Coliphages↗
PubMedDate not supplied

[Study of the mRNA-binding region of ribosomes at different steps of translation. II. Affinity modification of Escherichia coli ribosomes by benzylidene derivative of AUGU6 in the 70S initiation complex].

2',3'-O-(4-[N-(2-chloroethyl)-N-methylamino]) benzylidene derivative of AUGU6 was used for identification of the proteins in the region of the mRNA-binding centre of E. coli ribosomes. This derivative alkylated ribosomes (preferentially 30S ribosomal) with high efficiency within the 70S initiation complex. In both 30S and 50S ribosomal subunits proteins and rRNA were modified. Specificity of the alkylation of ribosomal proteins and rRNA with the reagent was proved by the inhibitory action of AUGU6. Using the method of two-dimensional electrophoresis in polyacrylamide gel the proteins S4, S12, S13, S14, S15, S18, S19 and S20/L26 which are labelled by the analog of mRNA were identified.

Alkylation↗
PubMedDate not supplied

[Inhibition of replication of human hepatitis B virus].

Several nucleoside 5'-triphosphate analogs were investigated as inhibitors of human hepatitis B virus replication. Different analogs inhibited DNA synthesis differently, 3'-azido-2',3'-dideoxythymidine 5'triphosphate being the most active compound. This inhibitor blocked DNA synthesis by 50% at inhibitor: substrate molar ratio 1:8, and by 80% - at 1:1. The hypothesis is formulated that 3'-azido-2',3'-dideoxythymidine 5'-triphosphate inhibits RNA directed viral DNA replication due to incorporation of this compound into 3'-termini of newly synthesized DNA chains. The phenomenon observed opens new possibilities for chemotherapy of acute and chronic human hepatitis B.

Antiviral Agents↗
PubMedDate not supplied

[Recognition of messenger RNAs upon initiation of translation in prokaryotes].

Structural aspects of ribosomal recognition of initiation sites on messenger RNA in procaryotes are considered. Location of initiation sites on mRNA, their length, typical nucleotide sequences that build up the initiation signal, and also the influence of the macrostructure of mRNA on protein synthesis are discussed. Determined nucleotide sequences of mRNA and DNA flanking the origin of different phage and bacterial genes are given.

Bacteria↗
PubMedDate not supplied

[Subjection of tetracycline resistance genes to cat promotor gene in plasmid pBR325].

A series of plasmids with tetracycline resistance genes (Tcr-operon) subjected to transcription from chloramphenicol acetyl transferase promoter (Cmr-promoter) have been constructed on the basis of plasmid pBR325, AprCmrTcr. For this purpose, a 0.8 Md fragment in pBR325 DNA bordered by unique EcoRI and HindIII restriction sites was cut out and structural genes of Tcr-operon were fused to the cat gene nucleotides corresponding to Cmr-promoter and first 72 amino acids of cat (alton, Vapnek, 1979; Marcoli et al., 1980). These plasmids with molecular weight amounting to 3 Md confer AprTcr phenotype to host cells. Tetracycline resistance can be eliminated completely by the deletion of a) Cmr-promoter; b) part of the first Tcr-operon gene.

Acetyltransferases↗
PubMedDate not supplied

[Comparative physiology of the replication of RNA-containing bacteriophages MS2 and Q beta].

The yield of the phage QB is always less than the yield of the phage MS2, the conditions of cultivation being similar. This is due to the fact that the yield of the phage QB from an infection centre is lower by a factor of 5--10 than the yield of the phage MS2. The yield of the phages may be increased by optimizing conditions of cultivation. The RNA-containg phages MS2 and QB were cultivated in the peptone-yeast growth medium in fermenters with the working volume of 30 and 50 litres. The yields were 2--5-10(13) particles/ml and 1--4-10(12) particles/ml for the phages MS2 and QB, respectively. The specific infectiveness of purified phage preparations was 2--4-10(12) particles/OD260 (MS2) and 2--4-10(11) particles/OD260 (QB).

Coliphages↗