CLONING AND MOLECULAR ANALYSIS OF PROMOTER-LIKE SEQUENCES ISOLATED FROM THE CHROMOSOMAL DNA OF LACTOBACILLUS-ACIDOPHILUS ATCC-4356

Promoter-like sequences from the chromosomal DNA of thermophilic strai n Lactobacillus acidophilus ATCC 4356 were cloned. Analysis of the thr ee DNA fragments showing promoter activity, designated P3, P6, and P15 , were performed in Lactobacillus reuteri, Lactococcus lactis, and E. coli. The reporter cat-86 gene was expressed in all three bacterial sp ecies under control of the fragments P3 and P6. Fragment P15 showed pr omoter activity only in Lactobacillus reuteri and E. coli but not in L actococcus lactis. The three host-specific transcriptional start point s (TSPs) were used when transcription of the cat-86 gene was controlle d by fragment P3 in Lactobacillus reuteri, E. colt, and Lactococcus la ctis. Similarly, fragment P15 initiated transcription of the cat-86 ge ne at two distinctive sites in Lactobacillus reuteri and E. coli. Only within fragment P6, a common TSP was used in Lactobacillus reuteri an d E. coli, but different from that used in Lactococcus lactis. Each TS P was preceded by the putative -35 and -10 hexamers. Computer analysis of the fragment P3 sequence revealed the existence of divergent promo terlike sequence (P3rev) located on the complementary DNA strand. Frag ments P6 and P15 were also functional in Lactobacillus acidophilus ATC C 4356 from which chromosomal DNA they were originally cloned.