[Substrate specificity and properties of methyl-directed site-specific dna endonucleases].

Methyl-directed site-specific DNA endonucleases (MD endonucleases) form a small group of enzymes which specifically cleave only methylated DNA. There are N6-methyladenine- and 5-methylcytosine-directed enzymes in this group. In spite of limited information on the MD endonucleases they are considered to be a very interesting subject for both fundamental investigations and practical use in biotechnology and epigenomics.

[Recombinant DNA-methyltransferase M1.Bst19I from Bacillus stearothermophilus 19: purification, propeties and amino acids sequence analysis].

The M1.Bst19I DNA-methyltransferase gene from restriction-modification system Bst19I (recognition sequence 5'-GCATC-3') in Bacillus stearothermophilus 19 has been cloned in the expressing vector pJW, that carries a tandem of thermo inducible promoters P(R)/P(L) from phage lambda. Highly purified enzyme has been isolated by chromatography on various resins from E.

[Purification of recombinant DNA methyltransferase M2.BstSE from nickase-modification system NM.BstSEI and study of the enzyme properties].

The operon of nickase-modification system from Bacillus stearothermophilus SE-589 (recognition site 5'-GAGTC-3') includes two DNA methyltransferase genes: bstSEIM1 and bstSEIM2. Gene encoding DNA methyltransferase M2.BstSEI was cloned in pJW vector and expressed in E.

[The Sse9I restriction-modification system: organization of genes and comparative analysis of proteins structures].

A nucleotide sequence was established for the full-length Sporosarcina species 9D operon coding for enzymes of type II restriction-modification system Sse9I. These enzymes recognize the tetranucleotide DNA sequence 5'-AATT-3'. The operon was shown to consist of three genes that are situated with the order: sse9IC-sse9IR-sse9IM and are transcribed in the same direction.

[Gene cloning, comparative analysis of the protein structures from Fsp4HI restriction-modification system and biochemical characterization of the recombinant DNA methyltransferase].

Genes coding for the restriction-modification system Fsp4HI, recognizing the sequence 5'-GCNGC-3' have been cloned in Escherichia coli ER2267 cells and its primary structure has been determined. This RM system consists of two genes: the DNA-methyltransferase gene which is followed by the restriction endonuclease gene in the same direction. The analysis of amino acid sequences of the proteins showed that M.

[Structure of Escherichia coli uracil DNA glycosylase and its complexes with nonhydrolyzable substrate analogues in solution observed by synchrotron small-angle X-ray scattering].

The structure of native and modified uracil DNA glycosylase from E. coli in solution was studied by synchrotron small-angle X-ray scattering. The modified enzyme (6His-uracyl DNA glycosylase) differs from the native one by the presence of an additional N-terminal 11-meric sequence amino acid residues including a block of six His residues.

[Determination and analysis of the primary structure of NM.BstSEI operone from Bacillus stearothermophilus SE-589 which produces N.BstSEI site-specific nickase].

Nucleotide sequence of Bacillus stearothermophilus SE-589 DNA fragment which includes an operone for site-specific NM-system with a gene for BstSEI nickase has been determined. Analysis of the regions adjacent to nickase gene has revealed two genes encoding DNA methyltransferases, which belong to different classes. Three genes which form system operone are separated with short open reading frames (ORFs).

[Restriction analysis of N-acetyltransferase 2 gene in Caucasian population of West Siberia].

Restriction analysis of the NAT2 gene was carried out in inhabitants of Novosibirsk. Polymorphism of this gene for nine known point mutations was studied in a sample of Novosibirsk residents consisting of 109 healthy Caucasians. The frequencies of these mutations did not significantly differ from the frequencies reported for Caucasian populations of other countries.

[Photoreactive dTTP analogues as substrates for thermostable DNA polymerase from Thermus thermophilus B35].

Substrate properties of several dTTP analogues bearing a photoreactive 2-nitro-5-azidobenzoyl (NAB) group attached at position 5 of uracil through linkers of various lengths, dTTP-NAB-x-dUTP (where x = 2, 4, 7-13 is the number of atoms in the linker), were studied. All the analogues are substrates for thermostable Thermus thermophilus B35 DNA polymerase in the elongation reaction of the 5'-32P-labeled primer-template complex. The kinetic parameters of some of the analogues were determined and compared with those of natural dTTP.

[Microorganisms of Lake Baikal and Lake Nyasa as indicators of anthropogenic influence: prospects of use in biotechnology].

Restriction endonucleases (RENs) were detected in 650 microbial strains isolated from water columns and bottom sediments of deep rift lakes, Baikal (Russia) and Nyasa (Southeastern Africa). They enzymes included unique (Fan I, Aca I, and Sse 91) and very rare (Bsi I, and Cci N I) species not typical of aquatic ecosystems. Water columns, deep cores, and bottom sediments of pure areas of the lakes contained no microorganisms with new RENs.

[Use of restriction endonucleases Bst2U I and Acc65 I to detect Kpn I polymorphism of NAT2 gene].

RFLP-analysis was made for 30 human DNA samples. The ability of application of restriction endonucleases Acc65I and Bst2UI to find point mutation C481T in NAT2 gene has been demonstrated for the first time. Variants of these enzymes application are discussed.

[Clinical and immunologic correlations of gastroduodenal lesions in patients with bronchial asthma].

To study local immunity of the stomach in bronchial asthma (BA) and the role of some immunity factors deficiency in development of gastroduodenal disturbances in BA patients, we have examined 271 male and female patients aged 18 to 60 years with exogenic and mixed BA of different severity. Gastroduodenal erosions were endoscopically diagnosed in 61 (22.5%) patients.

[The unique FauI restriction-modification system: cloning and comparative analysis of protein structure].

The nucleotide sequence was established for the full-length Flavobacterium aquatile operon coding for the FauI restriction-modification system. The operon is unusual in structure and has the gene order control protein gene-DNA methyltransferase A gene-restriction endonuclease gene-DNA methyltransferase B gene, other than in the known analogs. The genes are similarly oriented and overlap.

[Comparison of the homologous SfeI and LlaBI restriction-modification systems].

A fragment containing the SfeI restriction-modification system (RMS) operon was cloned from a Streptococcus faecalis SE72 plasmid. Nucleotide sequence analysis revealed its high (99.2%) homology to the operon for Lactococcus lactis subsp.

[Chromatin diminution is a key process explaining the eukaryotic genome size paradox and some mechanisms of genetic isolation].

The functions of redundant (junk, selfish, parasitic, etc.) DNA in eukaryotes can be reliably inferred from chromatin diminution (programmed elimination of up to 94% of the genome from somatic germ cells in Ascaris and Cyclops). These functions should be sought in germ cells, where this DNA is preserved during the entire life time of the species.

[Chromosomal radiosensitivity as associated with chromatin diminution in cyclops (Crustacea, Copepoda)].

Chromosomal radiosensitivity inferred from the yield of chromosome aberrations (CAs) was for the first time studied in Cyclops (Crustacea, Copepoda) before and after chromatin diminution (CD). A comparison was made for C. kolensis, in which CD denudes somatic embryo cells of the greatest (94%) DNA amount known for multicellular organisms, and C.

[M.BstF5I-4, the forth DNA methyltransferase of BstF5I restriction-modification system from Bacillus stearothermophilus F5].

The fourth DNA-methyltransferase of the BstF5I restriction-modification (RM) system from Bacillus stearothermophilus F5 (M.BstF5I-4) was discovered, which modifies the adenine residue within the upper strand of the recognition site 5'-GGATG-3'/5'-CATCC-3'. Thus, unlike other known RM systems, the BstF5I RM system comprises four genes encoding DNA-methyltransferases, three of which possess the same substrate specificity and methylate adenine within the 5'-GGATG sequence.

[Comparative study of the M.Bstf5I-1 and M.BstF5I-3 DNA methyltransferases from the Bacillus stearothermophilus F5 restriction-modification system].

The BstF5I restriction-modification system from Bacillus stearothermophilus F5, unlike all known restriction-modification systems, contains three genes encoding DNA methyltransferases. In addition to revealing two DNA methylases responsible for modification of adenine in different DNA strands, it has been first shown that one bacterial cell has two DNA methylases, M.BstF5I-1 and M.

[A rapid method for testing the activity of the repair enzyme uracil-DNA-glycosylase].

A rapid and effective method of testing of a repair enzyme, uracil-DNA-glycosylase, was proposed. As a substrate, a deoxyuridine-containing 5'-32P-labeled deoxyoligonucleotide covalently attached to a polystyrene support (Tenta Gel S-NH2) was used. The ammonia cleavage of the apyrimidine site formed in the enzymic reaction followed by the transition of the labeled oligonucleotide fragment from the solid phase into solution allowed the detection of the enzymic activity.

[New rare cutting restriction endonuclease SmII from Streptococcus milleri recognises 5'-ATTTAAAT-3'].

New restriction endonuclease (restrictase) Smil of type II was detected in the bacterial strain Streptococcus milleri. Cellular lysate enzyme cut T7 and adenovirus-2 DNAs at site 5'-ATTT decreases AAAT-3' but not lambda DNA which does not contain this sequence. Intense aeration inhibited the growth of S.