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The prtP-prtM intergenic region of Lactobacillus paracasei subsp. paracasei BGHN14 was cloned and sequenced. The nucleotide sequence of the prtP-prtM intergenic region in BGHN14, containing divergently orientated P prtP and P prtM promoters, was shorter by 35 bp in comparison with that in lactococci. The nucleotide sequence involved in casitone-dependent transcriptional regulation of the lactococcal prt genes was not found in the BGHN14. The activity of P prtM in L. lactis NZ9000 was very low and insignificantly changed in the presence of casitone, whereas P prtP was completely inactive. When L. casei ATCC393T was used as host, both P prtP and P prtM were active and strongly regulated by casitone. The results strongly indicate that the mechanisms of the casitone-dependent regulation of the prt genes in BGHN14 and lactococci are different. [ABSTRACT FROM AUTHOR]

The region of the prtR gene coding for the active site of PrtR proteinase was detected in natural isolates of lactobacilli, previously determined as Lactobacillus rhamnosus. This region was present in all L. rhamnosus strains with proteolytic activity. The PCR primers used were constructed on the basis of the sequence of the catalytic domain of the prtR proteinase gene. These primers generated in colony-PCR procedure specific 611-bp product with DNA from natural isolates of L. rhamnosus. No PCR amplifications using these primers were obtained for closely related bacteria of genus Lactobacillus, regardless of their proteolytic activity. In addition, these primers could be used singly or in multiplex PCR together with the Lactobacillus genus-specific primers. Compared with the other proteinases within the genus Lactobacillus (PrtP, PrtB and PrtH) which retained the activity in cell-free proteinase extracts, PrtR proteinase showed proteolytic activity only under in vivo conditions (whole cells of the producing strains). [ABSTRACT FROM AUTHOR]