Determination and comparison of Lactobacillus delbrueckii ssp. lactis DSM7290 promoter sequences

The transcriptional start points of ten Lactobacillus delbruckii ssp. lactis DSM7290 genes were determined by primer extension. The upstream located promoter regions, including potential −35 and −10 regions and the spacing between them were compared to the well-known Escherichia coli and Bacillus subtilis promoters. The Lb. delbruckii −35 consensus sequence (TTGACA) seems to be less conserved then the E. coli sequence. The nucleotides TGC were often found upstream of the −10 region (TATAAT). The most frequently observed spacing between the two core promoter regions was 17 nt and the main distance between the −10 region and the transcriptional start point was mostly determined to be 6 nt in contrast to 7 nt, as described for E. coli promoters. The preferred initiation nucleotides in Lb. delbruckii were shown to be definitely purines (A or G). The ribosome binding sites located downstream of the promoters revealed the consensus sequence 3′-UCCUCCU-5′, being the predicted 3′-OH end of the Lactobacillus 16S rRNA with a high degree of homology to known 16S rRNAs.