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A I Stepanov

Publications and source records attributed to A I Stepanov.

At least 19 recordsLinked to original sources
PubMed1994

Functional organization of the riboflavin biosynthesis operon from Bacillus subtilis SHgw.

We have sequenced 6006 bp DNA of a region from the Bacillus subtilis SHgw chromosome known to contain riboflavin biosynthesis genes (rib gene cluster, 210 degrees on the B. subtilis genetic map). Five of the seven open reading frames found within the sequence are shown to represent the genes ribG, ribB, ribA, ribH and ribTD. The calculated molecular masses for the putative translation products are 39,305, 23,481, 44,121, 16,287 and 14,574 daltons respectively. The five rib genes are transcribed as a polycistronic 4277 nucleotide messenger RNA. The steady-state level of the transcript is negatively regulated by riboflavin. A cis-acting element necessary for regulation was mapped by analysis of constitutive mutations within the 5' untranslated region of the operon. The element is at least 48 bp in length and does not bear obvious similarity to well defined prokaryotic regulatory elements. The molecular mechanism of regulation remains unknown, but the data presented argue against regulation by attenuation.

Bacillus subtilis↗
PubMed1990

[Expression of Photobacterium leiognathi bioluminescence system genes in Escherichia coli].

Expression of Photobacterium leiognathi bioluminescence genes under the control of lac, tac, tet promoters in Escherichia coli cells has been studied. The position of the genes for aliphatic aldehyde biosynthesis and for the synthesis of luciferase subunits was identified. The plasmid pBRPL1 has been constructed containing the system of bioluminescence genes devoid of promoter following the polylinker DNA fragment. The plasmid can be used for selection of promoter containing DNA sequences as well as for studying the promoters regulation in process of Escherichia coli cells growth.

Escherichia coli↗
PubMed1990

[Directed cloning of the HLA-B27 gene isolated from a patient with ankylosing spondylitis (Bechterew's disease)].

The authors have used the modified method of the direct gene cloning suggested by Nichols et al to isolate HLA-B27 gene from a patient suffering from ankylosing spondylitis. Five restriction enzymes (ClaI, HindIII, SnaBI, PvuI, SalGI) which had no recognition sites within the 6.0 kb EcoRI-BamHI-DNA fragment supposedly containing the HLA-B27 gene have been chosen by blotting-hybridization of the restriction fragments of the patients DNA with HLA-B27-specific probe. The 6.0 +/- 0.5 kb DNA fragments were isolated and cloned after the DNA treatment by 300 micrograms of all of these restriction enzymes. The obtained mini-library containing 280 recombinants has been screened with the use of HLA-B27 specific oligonucleotide probe. The clone PB27-2 has been isolated the restriction map of which is identical to HLA-B27k. The authors are planning to determine the sequence of the isolated gene in order to find a possible structural defect in it.

Cloning, Molecular↗
PubMed1989

[Expression of the Bacillus pumilus chloramphenicol acetyltransferase gene in Bacillus subtilis, achieved by the P-R-promotor of phage lambda].

The possibility of expression of the Bacillus pumilus chloramphenicol acetyltransferase gene (cat) in Bacillus subtilis from the pR promoter of phage lambda has been investigated in this work. For this purpose, the plasmid pPL703 carrying the B. pumilus DNA segment with the cat gene lacking promoter has been combined with the plasmid pBM21 containing the pR promoter. The recombinant plasmid pEL1 is capable of providing the 60 mkg/ml chloramphenicol resistance in Bac. subtilis cells.

Bacillus↗
PubMed1987

[Isolation and characteristics of a plasmid from the thermotolerant strain of Bacillus licheniformis].

A 8.3 kb cryptic plasmid was isolated from the thermotolerant strain of Bacillus licheniformis 28KA and designated pLT83. The replicative (rep) region was localized on the plasmid map. The pLT83 plasmid labelled in vitro with an antibiotic resistance determinant is able to replicate in B. subtilis cells. The pLT83 plasmid replicates stably in B. licheniformis strain at higher temperatures (37-60 degrees C) than in B. subtilis cells (37-50 degrees C). The plasmid and its derivatives may be used as vectors for gene cloning in B. subtilis and B. licheniformis cells.

Bacillus↗
PubMed1987

[Study of the 210-degree region of the Bacillus subtilis chromosome using recombinant plasmids].

The 210 degrees region of Bacillus subtilis DNA containing the rib operon and genes for the first (dapA) and last (lysA) steps of lysine biosynthesis was cloned. PstI fragments of B. subtilis m.m. 4.7 MD DNA containing the lys and the proximal part of rib operon were isolated from different B. subtilis strains (SB25 and SHgW) and shown to have the same restriction and genetic maps. The restriction mapping of EcoRI fragment of B. subtilis m.m. 6.3 MD DNA containing the rib operon has been carried out.

Bacillus subtilis↗
PubMed1985

[Effect of the pC194 plasmid on the development of Bacillus thuringiensis phages].

Bacillus thuringiensis var. galleriae strains were transformed by plasmid pC194, coding for chloramphenicol resistance (CmR). Efficiency of plating and the yields of bacteriophages Tg13 and Tg27 maturating in CmR transformant cells were decreased for 2-3 orders as compared with the ones in parental strains. The CmR transformants are characterized by the increased level of spontaneous induction of bacteriophage Tg22.

Bacillus thuringiensis↗
PubMed1985

[Riboflavin operon in Bacillus subtilis contains additional promoters].

Using the methods of molecular cloning permitted to show that riboflavin operon of Bacillus subtilis contains four promoters. Three of them are functionally active in the Bacillus subtilis system. The main promoter of the operon with regulatory region was cloned in plasmid pPL603. Cells containing the constructed plasmid pGM32 are resistant to chloramphenicol. The level of resistance is regulated by concentration of riboflavin (the effector of operon). The following model of rib-operon has been proposed: (Formula: see text).

Bacillus subtilis↗
PubMed1983

[3 linkage groups of the genes of riboflavin biosynthesis in Escherichia coli].

Using transposon Tn5 inactivation technology a collection of Escherichia coli mutants defective in riboflavine biosynthesis was obtained. All mutations were distributed within three linkage groups. With the help of P1-transduction mapping, group I mutations (ribA locus) were localized near cysB locus (28 min of the standard 100 min E. coli map) and mutations of group II (ribB locus) were mapped near tolC locus (66 min). The location of group III mutations was approximately determined by the F' complementation analysis: this linkage group lies in the region of 56-60 min of the E. coli map.

Chromosome Mapping↗
PubMed1982

[Location of the traS- and finO-type genes and of the oriT region of plasmid R6K].

The regions of B6K DNA corresponding to oriT, finO and traS are mapped using a number of hybrid plasmids and deletion mutants pAS3::Tn5, pAS3::Tn7 and pAS3::Tn9 obtained in vitro after treatment with restriction endonucleases EcoRI and BamHI. FinO- and traS-like genes were mapped in the regions of 10 and 25,0-25,4 MD, respectively, oriT being situated in the region of 4,6-4,7 Md.

Chromosome Deletion↗
PubMed1982

[Bacillus subtilis mutants resistant to roseoflavin].

Bacillus subtilis mutants resistant to 100 mkg/ml of roseoflavin/8-dimethylamino (nor) riboflavin/have been shown to excrete 0.5 to 20 mkg/ml riboflavin and small amounts of FMN and FAD into the culture medium. The rosR mutations are localized in the operator region of riboflavin operon. The combination of rosR and ribC mutations (the latter being mutation in the regulator gene) leads to hyperproduction of riboflavin.

Anti-Bacterial Agents↗