[Isoforms of Bacillus subtilis IMV B-7014 lectin].

The subunit organization and regulatory features of extracellular sialic acid specific lectin produced by saprophytic strains Bacillus subtilis IMV B-7014 have been investigated. Autofocusing method was used to identify three lectin isoforms that were distinguished by physicochemical and biological properties. Using the transcription system in vitro it was established that one of the targets of bacterial lectin action was DNA-dependent RNA-synthesis. Lectin isoforms affect differently the synthesis: from its full inhibition to the absence of the effect on the yield of RNA-transcription product.

[Lectins from Sambucus nigra L inflorescences: isolation and investigation of biological activity using procaryotic test-systems].

Isolation of lectins from extracts of the Sambucus nigra inflorescences and of pollen material have been performed using isoelectric focusing without carrier ampholytes (autofocusing). Fractions active in agglutination tests with different carbohydrate specificity were subjected to SDS-PAGE. The major lectin found in whole inflores-cences was GalNAc specific and is proposed to be a heterotetramer with subunits of about 30 and 33 kDa. It was called SNAflu-I. At least two other lectins were present in the pollen material and supposed to consist of identical subunits. Major positively charged lectin was Glc/Man specific with subunit of 26 kDa and called SNApol-I. Other pollen component (SNApol-II) was Gal specific with subunit of about 20 kDa. In order to elucidate cell targets sensitive for the S. nigra lectin's activity the combined effects of the lectins and transcriptional of phenazine origin on B. subtilis cells growth have been studied. Only SNApol-I demonstrated the antagonistic activity against these inhibitors in vivo. This lectin but not the SNAflu-I can also inhibit transcription in vitro. It is supposed that lectins from the same source may act in different directions on cell metabolism. Particularly one of the common targets may be the DNA-dependent synthesis of RNA.

[Regulatory properties of Bacillus subtilis isolectins].

The ability of natural and mutant Bacillus subtilis cultures with imperfect reparation/recombination system to synthesis of extracellular and surface lectins was investigated, and dependence of lectin production process on cultures' genotype was proved. Mutant B. subtilis recP has practically lost its ability to produce the extracellular lectins as a result of mutation of a gene of the reparation/recombination system. The application of the method "autofocusing" allowed to investigate all the spectrum oflectin molecular forms of natural B. subtilis culture and to reveal isoforms distinguished by physico-chemical and hemagglutination properties. It was shown that lectin cathode forms inhibit the transcription process from plasmid promnoter completely, and anodic forms activate the transcript formation slightly in the transcription in vitro with T7 bacteriophage DNA-dependent RNA-polymerase.

[Investigation of Bacillus subtilis exolectin ability to modulate the antibiotics effect on growth of Bacillus subtilis mutants].

The ability of Bacillus subtilis exolectin to modulate the effect of antibiotics acting as metabolic inhibitors, which can suppress the biosynthesis of cell wall glycans (ampycillin), replication (mitomycin C) and transcription (rifampycin), have been investigated on mutants of B. subtilis. Extracellular lectin was produced by B. subtilis strains B-7014 isolated from new-born calve's intestines. It was shown that the exolectin displays affinity for to sialic and uronic acids in the decreasing order: mucin, glycuronic acid, N-acetylneuraminic acid, galacturonic acid. It was established by the diffusion method and by determination of minimum inhibitory concentrations (MIC) that B. subtilis exolectin had selective activity as to bacteriostatic effect of antibiotics under study. The activity depended on the antibiotic structure and on mutant genotype defective as to the state of its replication and repair system. The lectin under study had no modulating effect on ampycillin action. There was a tendency to lower the bacteriostatic effect of rifampycin on the growth of strain BD170 (rec+) with the help of exolectin. Only in the case of mitomycin C the significant modulating effect of the bacterial lectin was manifested and its dependence on the mutant genotype was shown. The mutants sensitivity to exolectin effect decreased in the order: BD293 (polC), SB25 (recP), BD224 (recE), BD170 (rec+). Revealed ability of B. subtilis exolectin to protect the action of mitomycin C on growth of mutant BD293 (polC) with defect in the enzyme-DNA polymerase III permits supposing that the process of DNA replication is the most sensitive target for the lectin. The found dependence of modulation of the mitomycin C effect by the bacterial lectin on the genotype of mutants (rec-) demonstrated that the lectin acted following a complex mechanism mediated by a replicative and reparative complex.

[Lectins modulate the cytostatic action of the composite bioregulators-conjugates of azaanalogues of pyrimidine and phenazine-1-carboxilic acid in Bacillus subtilis test-system].

The idea of the work was to study a combined effect of some lectins (Con A, PHA, STA, WGA, SNA, VAA) and new composite bioregulators (PhCA-1 and azapyrimidine derivatives) on growth of Bacillus subtilis cells in order to elucidate cell targets sensitive to lectin's activity. Study of combined effects of high- and low-molecular bioregulators may also be the subject of practical interest with a prospect of obtaining new bacterio-and carcinostatic drugs. Using B. subtilis mutants it was shown that lectins can modulate the cytostatic effect of initial substanses and their pyrimidine derivatives in the range: phenazine < PhCA-1 < 6-azacytosine derivative of PhCA-1 < 6-azauracyl derivative of PhCA-1. This modulating effect was absent in recP mutant, which has lost the ability to produce its own bacterial lectin, demonstrating its possible role as a mediator. The antagonistic effect of all plant lectins under study on cytostatic action of <6-azauracyl derivative of PhCA-1 in rec+ culture was observed as the result of possible competition for some common target. As both the B. subtilis lectin and the low-molecular bioregulator can inhibit transcription in vitro, it is supposed that their common target may be the DNA-dependent synthesis of RNA.

[Ability of lectins to model the action of antibiotics on growth of mutants of Bacillus subtilis].

Using the bacterium B. subtilis as a model and antibiotics as metabolic inhibitors which can suppress replication (mitomycin), transcription (rifampycin) or translation (streptomycin), it is shown that carbohydrate-binding proteins (lectins of plant origin) have different action on intracellular processes under study. The effect depends on lectin's structure and on the condition of bacterial reparation/recombination system. Lectins with chitin-binding domain (STA, WGA) is characterized by the most expressed effect on the repair-proficient strain when the inhibitor of template function of DNA (mitomycin C) was used. The absence of such effect on mutants recP and polC may prove that the corresponding bacterial proteins play the role of mediators in transmission of the signal influence of lectins. The representative of ribosome-inactivating lectins--SNA-I--could increase the streptomycin effect. It is proposed that intracellular effects of lectins have complex mechanisms which need participation of repair functions.