[Synthesis of 3'-mercapto-2',3'-dideoxynucleoside-5'-triphosphates and their properties in DNA synthesis with RNA-dependent DNA polymerases]. / Sintez 3'-merkapto-2',3'-didezoksinukleozid-5'-trifosfatov i ikh svoistva v sinteze DNK s RNK-zavisimymi DNK-polimerazmi.

3'-Mercapto-2',3'-dideoxy-NTP were synthesized and tested as DNA chain terminating nucleotides. It is shown that the analogues selectively and irreversibly terminate DNA chain elongation by AMV and HIV reverse transcriptases and terminal deoxynucleotidyl transferase, whereas calf thymus alpha DNA polymerase, E. coli DNA polymerase I (Klenow fragment) and MLV reverse transcriptase do not use the nucleotide analogues as chain terminator substrates.

[Rare codons and gene expression in Escherichia coli]. / Redkie kodony i ékspressiia genov v Escherichia coli.

Influence of rare codons upon gene expression in E. coli was investigated. The chimeric gene was created combining CAT gene and a fragment of the gene, encoding for alpha-domain of beta-galactosidase. The synthetic oligonucleotides were inserted in different parts of the chimeric gene. The constructed synthetic oligonucleotides encoded the same amino acid sequences and contained arginine codons AGG, AGA and CGT in various combinations. It was shown that the presence of rare arginine codons AGG and AGA in the template and their mutual arrangement significantly influence the level of gene expression. At the same time the presence of leucine, isoleucine, glycine and proline rare codons does not cause such an effect. Translation of AGGAGG and AGAAGA sequences was found to lead to the formation of a considerable amount of polypeptides of incomplete length. It was shown that the presence of such a cluster of rare codons effects on the length of specific mRNA.

[Mutual location of the rRNA operon and tuf gene in the Mycoplasma gallisepticum strain S6 genome]. / Vzaimnoe raspolozhenie operona rRNK i gena tuf v genome Mycoplasma gallisepticum, shtamm S6.

The genomic library of Mycoplasma gallisepticum was constructed and two clones, selected by hybridization on E. coli 16S rRNA, were analyzed. The restriction map of the clones indicate that both clones belong to the same region of the M. gallisepticum genome. The results of Southern hybridization with either E. coli 16S rRNA, or E. coli 23S rRNA, or oligonucleotide synthesized as a part of M. gallisepticum 5S rRNA, led to the conclusion that the unspliced rRNA operon was cloned. The order of genes in the operon is common for eubacteria: 16S-23S-5S. The tuf gene of M. gallisepticum was mapped inside the cloned region 5 kb upstream of 16S gene by hydridization on E. coli tufA gene and oligonucleotide synthesized on the basis of M. gallisepticum tuf gene sequence. The direction of transcription of the gene and the expected direction of transcription of the rRNA operon coincide.

[3'-Mercapto-3'-deoxythymidine-5'-triphosphate as a terminator of DNA synthesis catalyzed by RNA-dependent DNA-polymerases]. / 3'-Merkapto-3'-dezoksitimidin-5'-trifosfat kak terminator sinteza DNK, kataliziruemogo RNK-zavisimymi DNK-polimerazami.

3'-Mercapto-3'-deoxy-TTP was synthesized and tested as DNA chain terminator nucleotide for calf thymus alpha DNA polymerase, E. coli DNA polymerase I (Klenow fragment), terminal deoxyribonucleotidyltransferase (Bollum enzyme) and reverse transcriptase from AMV- and HIV-I-viruses. It was shown that the compound terminates DNA chain elongation by reverse transcriptases selectively and irreversibly. Other tested DNA polymerases do not use this nucleotide analogue as a substrate. 3'-Mercapto-3'-deoxythymidine was tested on lymphoblastoid T-cell line MT-4 with HIV-viruses and shown to suppress viruses as efficiently as 3'-azido-3'-deoxythymidine.