Analysis of promoter sequences from Lactobacillus and Lactococcus and their activity in several Lactobacillus species

Promoter-active fragments were isolated from the genome of the probiotic or ganism Lactobacillus rhamnosus strain GG using the promoter-probe vector pN Z272. These promoter elements, together with a promoter fragment isolated f rom the vaginal strain Lactobacillus fermentum BR11 and two previously defi ned promoters (Lactococcus lactis lacA and Lacrobacillus acidophilus ATCC 4 356 slpA), were introduced into three strains of Lacrobacillus. Primer-exte nsion analysis was used to map the transcriptional start site for each prom oter. All promoter fragments tested were functional in each of the three la ctobacilli and a purine residue was used to initiate transcription in most cases. The promoter elements encompassed a 52- to 1140-fold range in promot er activity depending on the host strain. Lactobacillus promoters were furt her examined by surveying previously mapped sequences for conserved base po sitions. The Lactobucillus hexamer regions (-35: TTgaca and -10: TAtAAT) cl osely resembled those of Escherichia coli and Bacillus subtilis, with the h ighest degree of agreement at the -10 hexamer The TG dinucleotide upstream of the -10 hexamer was conserved in 26% of Lactobacillus promoters studied, but conservation rates differed between species. The region upstream of th e -35 hexamer of Lactobacillus promoters showed conservation with the bacte rial UP element.