PSEUDOMONAS-AERUGINOSA LASA GENE - DETERMINATION OF THE TRANSCRIPTIONSTART POINT AND ANALYSIS OF THE PROMOTER REGULATORY REGION

The elastolytic activity of the opportunistic pathogen Pseudomonas aer uginosa is due to the combined activities of at least three secreted p roteins: elastase, LasA and alkaline protease. Transcription of both t he lasA gene and the elastase structural gene, lasB, requires the tran scriptional activator LasR. In order to localize the promoter elements involved in lasA expression, the transcription start point (tsp) for lasA was localized by S1 protection and primer extension analysis. The DNA sequence of the region upstream from the tsp was determined, and a putative sigma70 promoter was identified. Sequence comparison with t he lasB promoter region revealed two areas of considerable homology wh ich could act as potential binding sites for LasR or other, as yet uni dentified, regulatory proteins.