Xanthomonas oryzae pv. oryzae recA is transcribed and regulated from multiple promoters

Transcription regulation of Xanthomonas oryzae pv. oryzae recA was characte rized. Primer extension experiments showed that rec is transcribed from thr ee promoters designated P1, P2 and P3. The sequences of -10 and -35 regions of these promoters have moderate homology to the proposed consensus sequen ce for a Xanthomonas promoter. Putative SOS boxes were identified in the vi cinity of P1 and P2 promoters. Deletion analysis and in vivo monitoring of promoter activity of these promoters revealed that the three promoters have different characteristics. P1 and P2 show stress-inducible high and low pr omoter strengths respectively. P3 is a non-inducible moderate promoter stre ngth. These promoters are regulated by two SOS boxes. The multiplicity of p romoters and SOS boxes provides back-up systems to ensure proper regulation of recA. (C) 2001 Federation of European Microbiological Societies. Publis hed by Elsevier Science B.V. All rights reserved.