Characterization of the transfer-related <Emphasis Type="Italic">tra</Emphasis> region of the conjugative plasmid p19 from a <Emphasis Type="Italic">Bacillus subtilis</Emphasis> soil strain

The nucleotide sequences of three DNA fragments (total size 30574 bp) of the plasmid p19 from the Bacillus subtilis 19 soil strain have been determined. Thirty open reading frames (ORFs) have been identified in these fragments. oriT of the plasmid has also been identified. As shown by the search for homologs of hypothetical protein products of these ORFs in databases, such homology exists for 18 ORFs. The protein products of nine ORFs can be assumed to have specific functions. Several ORFs were inactivated via insertional mutagenesis, and the conjugation capacity of the mutant plasmids was estimated. According to the data on homology of protein products and the results of ORF inactivation, regions of a total size of about 20 kb from the DNA fragments sequenced by us were inferred to belong to the tra region of p19. As follows from the analysis of the identified ORFs of the p19 tra region, it differs from the earlier described tra regions of other plasmids, irrespective of a certain similarity with the corresponding regions of plasmids of gram-positive bacteria from the genera Bacillus, Clostridium, and Listeria.