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.