[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. These genes encode the control protein (C.Sse9I), restriction endonuclease (R.Sse9I) and DNA-methyltransferase (M.Sse9I), respectively. A specific DNA sequence (C-box) presumably recognized by C-protein was found immediately upstream of sse9IC gene. The comparative analysis of amino acid sequences of C.Sse9I and R.Sse9I with those of relative proteins has been done. It was found that R.Sse9I revealed the most homology with the segments of R.MunI (5'-CAATTG-3') and R.EcoRI (5'-GAATTC-3'), where amino acid residues, responsible for recogniton of AATT core sequence are located. The sse9IR gene was cloned into the temperature-inducible expression vector, and recombinant Sse9I restriction endonuclease preparation was isolated.

BstF5I, an unusual isoschizomer of FokI.

BstF5I, a new restriction endonuclease (ENase) from Bacillus stearothermophilus F5, has been discovered. This enzyme recognizes 5'-GGATG-3' and cleaves DNA, generating a 2-base 3'extension: 5'-GGATG NN[symbol: see text]-3' 3'-CCTAC[symbol: see text]NN-5' BstF5I is an isoschizomer of FokI and seems to be evolutionarily close to other nonpalindromic-recognizing ENases from thermophilic bacilli.

CciNI, an isoschizomer of NotI from Curtobacterium citreum recognizes 5'-GC decreases GGCCGC-3'.

CciNI, an isoschizomer of NotI, has been isolated from Curtobacterium citreum. The enzyme cleaves within the recognition sequence 5'-GC decreases GGCCGC-3' as indicated by the arrow.

[Effect of poly(dA).poly(dT) sequence inserted into EcoR1 site of pBr322 plasmid on the expression of tet and bla genes]. / Vliianie posledovatel'nosti poli(dA).poli(dT), vstroennoi v EcoR1-uchastok plazmidy pBR322, na ékspressiiu genov tet i bla.

The 99 base pair poly(dA).poly(dT) stretch was inserted into EcoRI site of pBR plasmid. The effect of this insertion on tet-gene expression from P2 promoter, and bla-gene expression from P1 and P3 promoters was studied. The insertion results in a slight enhancement of the resistance of the cells to tetracycline and a decreased sensitivity to ampicillin. It is suggested that these findings reflect the effect of insertion on the transcription of the corresponding genes.

[Effectiveness of the promoter Ptac' in vitro and in mini-cells]. / Izuchenie éffektivnosti promotora Ptac' in vitro i v mini-kletkakh.

The efficiency of hybrid promotor Ptac', comprising a synthetic trp-promoter and lacUV5 "-10" sequence, was studied. By means of electrophoresis and hybridization of RNA-products obtained in vitro and in minicells, with promotor-containing plasmids; the hybrid promotor was found to be 6 times and 3-4 times as efficient as trp and lacUV5 promoters, respectively.

[Circular transcription map of the plasmid pBR322]. / Kol'tsevaia transkriptsionnaia karta plazmidy pBR322.

The plasmid pBR322 transcription in the isolated E. coli DNA-dependent RNA-polymerase system was studied. Transcription regions as well as transcripts orientation were defined using both the technique of "criss-cross" hybridization and the annealing of RNA-products with L- and H-strands of plasmid. Summing up obtained data together with available data on promoter localization a circular transcription map of plasmid pBR322 was constructed. Effects of heparin, ion strength and E. coli S-30 system on in vitro transcripts were also studied. The 110-long RNA transcript synthesized in Ori region of pBR322 was found to be the most sensitive to all these factors. RNA-transcripts obtained in in vitro system are able to direct protein synthesis in cell-free S-30 system.

[Col E1 DNA transcription in Escherichia coli RNA-polymerase system in vitro]. / Issledovanie transkriptsii DNK plazmidy ColEI v sisteme RNK-polimerazy Escherichia coli.

The ColEI plasmid DNA transcription in E. coli RNA-polymerase system in vitro was studied. Three RNA types: of 110-140 residues long, 1700 residues long and of the length similar to that of DNA-template were synthesized in the reaction, containing 10 mM MgCl2, 50 mM KCl and 15% glycerol. The transcription was shown to be asymmetric, the DNA H-chain being transcribed. The ColEI DNA region transcribed in vitro was located by the blotting techniques. This region comprised most of the ColEI genome except the colicin EI gene. The addition of mitomycin C to the reaction mixture caused only a little stimulation of colicin EI gene transcription. Four fragments of HaeIII digest of ColEI DNA were shown to have affinity to RNA-polymerase in the absence of NTPs and two fragments to have it in the presence of 3 NTPs (in the RNA initiation conditions). These two fragments seem to contain two strong promoters. One of them is in the HaeIIIA fragment, where the colicin EI gene origin is situated, and another one is the HaeIIIB fragment (in the immunity region).

[Conversion of nucleoside triphosphates in an RNA polymerase system]. / O prevrashcheniiakh nukleozidtrifosfatov v RNK-polimeraznoi sisteme.

The behavior of nucleoside triphosphates (NTP) in the RNA-polymerase system from E. coli was studied. The conversion of NTP to the corresponding nucleoside diphosphate (NDP) was observed. This phenomenon was accounted for a contaminating enzyme activity in the RNA-polymerase preparations. The possibility to remove such a contamination was demonstrated, the best technique being the DNA-cellulose affinity chromatography. The purified enzyme does not catalyze the intermediate formation of NDP's from NTP's during RNA synthesis with poly(U) and poly(dG)-poly(dC) as templates.

Study of the relationship between the subfraction composition of histone F1 and the type of tissue in birds.

The subfraction composition of lysine-rich histone has been studied with the aid of polyacrylamide gel electrophoresis. The subfraction compositions of the histone F1 of several tissues from the chicken, pigeon, and titmouse have been compared. The histone F1 from the tissues investigated consists of four or five subfractions of similar number and electrophoretic mobility (1, 1a, 2, 3, and 4). In the different avian species each subfraction varied its mobility independently of the others. The chicken tissues investigated can be divided into two classes, depending on the relative concentration of subfractions 2 and 3 (A and B): Class A (subfraction 2 is smaller than 3) includes the brain, liver, skeletal muscle, heart, muscular layer of the stomach, and pancreas, and class B (subfraction 2 is larger than 3) includes the intestinal mucosa, thymus, and testes, as well as the liver, heart, and pancreas from a 21-day embryo. Such a division of the tissues corresponds to the varying rate of their cellular renewal. In a parallel examination of the relative concentrations of the individual subfractions in the same tissues from the three avian species it has been found that the relative concentration of subfractions 3 and 2 is increased in the skeletal muscles, heart, brain, and liver, that subfraction 2 is increased in the intestinal mucosa, that subfractions 4 and 3 are increased in the pancreas, and that subfractions 1, 1a, and 4 are increased in the erythrocytes. The results obtained may be interpreted as a consequence of some relationship between the subfraction composition of histone F1 and the type of tissue of the source.