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D A Perumov

Publications and source records attributed to D A Perumov.

At least 19 recordsLinked to original sources
PubMed2004

[Study of the mechanism for regulating ribR gene activity in Bacillus subtilis].

Analysis of the phenotypic manifestation of inactivation of several genes from the ytlI-ytnM operon containing the ribR gene and results of Northern hybridization showed that the ribR gene does not have the self promoter and is transcribed from the main promoter of the ytlI-ytnM operon. Two sites of single nucleotide substitutions leading to derepresson of ribR gene were identified between the putative main promoter and transcription start of the ytlI-ytnM operon regulatory region.

Bacillus subtilis↗
PubMed2003

Main physicochemical features of monofunctional flavokinase from Bacillus subtilis.

The main properties of a monofunctional riboflavin kinase from B. subtilis have been studied for the first time; the enzyme is responsible for a key reaction in flavin biosynthesis--the ATP-dependent phosphorylation of riboflavin with production of flavin mononucleotide. The active form of the enzyme is a monomer with molecular weight of about 26 kD with a strict specificity for reduced riboflavin. To display its maximum activity, the enzyme needs ATP and Mg(2+). During the phosphorylation of riboflavin, Mg(2+) could be partially replaced by ions of other bivalent metals, the efficiencies of which decreased in the series Mg(2+) > Mn(2+) > Zn(2+), whereas Co(2+) and Ca2+ had inhibiting effects. The flavokinase activity was maximal at pH 8.5 and 52 degrees C. ATP could be partially replaced by other triphosphates, their donor activity decreasing in the series: ATP > dATP > CTP > UTP. The Michaelis constants for riboflavin and ATP were 0.15 and 112 micro M, respectively. As compared to riboflavin, a tenfold excess of its analog 7,8-dimethyl-10-(O-methylacetoxime)-isoalloxazine decreased the enzyme activity by 30%. Other analogs of riboflavin failed to markedly affect the enzyme activity.

Adenosine Triphosphate↗
PubMed1999

The ribR gene encodes a monofunctional riboflavin kinase which is involved in regulation of the Bacillus subtilis riboflavin operon.

A 3.5 kb EcoRI-BamHI fragment of Bacillus subtilis chromosomal DNA carrying the ribR gene, involved in regulation of the B. subtilis riboflavin operon, was cloned in the B. subtilis-Escherichia coli shuttle vector pCB20. DNA sequence analysis of this fragment revealed several ORFs, one of which encodes a polypeptide of 230 amino acids with up to 45% sequence identity with FAD synthetases from a number of micro-organisms, such as Corynebacterium ammoniagenes, E. coli and Pseudomonas fluorescens, and also to the ribC gene product of B. subtilis. The ribR gene was amplified by PCR, cloned and expressed in E. coli. Measurement of flavokinase activity in cell extracts demonstrated that ribR encodes a monofunctional flavokinase which converts riboflavin into FMN but not to FAD, and is specific for the reduced form of riboflavin.

Amino Acid Sequence↗
PubMed1998

[Cloning and biochemical identification of the ribR gene in Bacillus subtilis].

The PCR copy of the ribR gene of Bacillus subtilis was subcloned in Escherichia coli cells under the control of the phage T7 inducible promoter. The polypeptide of 26 kDa corresponding to the 690-bp gene is the product of the ribR gene. The protein encoded by the ribR gene is flavokinase, and the riboflavin-reduced form is the substrate for it.

Amino Acid Sequence↗
PubMed1997

[Phenotypic expression of a 100-pair nucleotide deletion in the regulatory region of the Bacillus subtilis riboflavin operon].

Assessment of specific activity of riboflavin synthase and the level of riboflavin accumulation in strains with a 110-nucleotide deletion in the regulatory region of the riboflavin operon showed that this deletion specified semi-constitutive expression of the operon. This was assumed to be connected with the elimination of three nucleotides from a potential transcription antiterminator.

Amino Acid Sequence↗
PubMed1997

[Cloning of ribR, an additional regulatory gene of the Bacillus subtilis riboflavin operon].

A 13.0-kb EcoRI fragment of Bacillus subtilis DNA carrying an additional regulatory ribR gene of riboflavin operon was cloned on the basis of resistance to 7, 8-dimethyl-10 (O-methylacetoxym)-isoalloxasin. The cloned fragment was trans-dominant with regard to ribC constitutive mutations that block the overproduction of riboflavin but inactive relative to constitutive mutations in the rib(O) regulatory region.

Bacillus subtilis↗
PubMed1997

[Analysis of the primary structure of the supplementary regulatory region of the riboflavin operon in Bacillus subtilis].

The sequencing of a 3.5 kb EcoRI-BamHI fragment located in the 236 degrees region of the Bacillus subtilis chromosome revealed a 690-bp long open reading frame, partly similar in amino acid composition to flavokinases/FAD synthases from several microorganisms. The discovered sequence can be identified with the gene ribR, an auxiliary regulatory gene of the riboflavin operon of Bacillus subtilis.

Amino Acid Sequence↗
PubMed1996

[Genetic mapping of an additional regulatory locus of the riboflavin operon of Bacillus subtilis].

Two mutations designated ribR5 and ribR6, which effectively decrease the constitutive expression of the Bacillus subtilis riboflavin operon, were mapped in the 236 degrees region of the B. subtilis genetic map based on linkage analysis with respect to the apt6 marker. Cotransfer indices for the ribR5 and ribR6 markers and apt6 suggest that both ribR mutations are alleles of exactly the same genetic locus. Total results of transductional and transformational crosses indicate the following marker order: pheA-apt6-ribR-azlB-aroD4. Phenotypic peculiarities of the ribR mutants allow us to assume that they belong to an additional subunit of the regulatory protein of the riboflavin operon.

Bacillus subtilis↗
PubMed1992

Riboflavin operon of Bacillus subtilis: unusual symmetric arrangement of the regulatory region.

Seventeen cis-dominant mutations leading to riboflavin overproduction in Bacillus subtilis were localized to the region between nucleotides +37 and +159 relative to the transcription initiation site of the riboflavin operon. This region displays an unusual structure for regulatory sequences. The main part of it represents clusters of A/T and G/C-rich sequences that symmetrically blank a short inverted repeat.

Bacillus subtilis↗
PubMed1990

Genetic mapping of regulatory mutations of Bacillus subtilis riboflavin operon.

Seven mutations leading to riboflavin overproduction in Bacillus subtilis were found to be linked to the marker dnaF133 (145 degrees on the B. subtilis genetic map) by transformation. Cotransfer indexes (42.5%-61.7%) suggest that the ribC mutations are alleles of the same locus. Results of transduction and transformation crosses suggest the following order of markers:pyrD26-ts-6-dnaF133-ribC-recA1.

Alleles↗
PubMed1986

[Operon of riboflavin biosynthesis in Bacillus subtilis. XVII. A study of the regulatory functions of the intermediate products and their derivatives].

Repression of synthesis of GTP-cyclohydrolase and riboflavinsynthetase was studied in different regulatory mutants of Bacillus subtilis. The results of experiments with some riboflavin precursors and their derivatives revealed that 5-amino-2,6-dioxo-4-ribitylaminopyrimidine and 6-methyl-7-(1',2'-dioxyethyl)-8-ribityllumazine can serve as effectors in riboflavin biosynthesis.

Bacillus subtilis↗
PubMed1985

[Mutagenic effect of o-methylhydroxylamine on the prophage and extracellular phage lambda].

Induction of c-mutations in extracellular bacteriophage and prophage lambda cI857 ind-treated with 1 M O-methylhydroxylamine (OMHA) at 32 degrees and pH 5.6 has been studied. The frequency of c-mutations increases proportionally to the time of treatment of extracellular phage and does not depend on cellular recA+ or polA+ functions and on induction of SOS-repair system caused by UV-irradiation of host cells. Prophage is inactivated and mutagenized approximately 10-fold faster than extracellular phage immediately after treatment of lysogenic cells during prophage induction. Thus, prophage survival does not depend on repair functions of the host cells, and the frequency of c-mutations in recA and, especially, in polA lysogens is significantly lower, than in the wild-type cells. Delayed thermoinduction (90 min) of prophage causes significant enhancement of survival and decreases the frequency of c-mutations in all strains studied. Preliminary treatment of non-lysogens with OMHA does not increase the frequency of c-mutations in undamaged phage or in phage treated with OMHA in vitro.

Bacteriophage lambda↗
PubMed1984

[Effect of O-hydroxylamine on the transforming DNA from Bacillus subtilis. Correlation of chemical modifications with genetic consequences].

The action of methoxyamine (MA) on B. subtilis transforming DNA (50 degrees C, pH 4,5 and 6,0, 1 M MA) was studied. The rate of cytosine residues modification in DNA is 250 times less than in monomer (rate constants for DNA are 1,5 X 10(-1) min-1 at pH 4,5, and 2,5 X 10(-6) min-1 in the first 300 hours of treatment at pH 6,0). At pH 4,5 the rates of cytosine (I) conversion into N4-methoxycytosine (II) and into 6-methoxyamino-5,6-dihydro-N4-methoxycytosine (III) are constant (II/III ratio is about 2,1). At pH 6,0 the II/III ratio smoothly increases from 1,0 to 1,6 (200 and 900 hours of treatment) due to a decrease in the product III accumulation rate. The frequency of MA-induced mutations shows a bell-shaped dependence on time with maxima (approximately 10%) at 80 (pH 4,5) and 500 (pH 6,0) hours of treatment. In both cases approximately 10% of cytosine residues are modified. These results suggest that either compound III is efficiently removed from the transforming DNA, or its presence does not arrest the DNA replication.

Bacillus subtilis↗