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 PprtP and PprtM/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 PprtM in L. lactis NZ9000 was very low and insignificantly changed in the presence of casitone, whereas PprtP was completely inactive. When L. casei ATCC393T was used as host, both PprtP and PprtM 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.
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