Open AccessHomology between nucleotide sequences of promoter regions of nah and sal operons of NAH7 plasmid of Pseudomonas putida.
Author(s) -
Mark A. Schell
Publication year - 1986
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.83.2.369
Subject(s) - operon , biology , homology (biology) , genetics , promoter , plasmid , gene , transcription (linguistics) , nucleic acid sequence , base pair , microbiology and biotechnology , consensus sequence , transposable element , escherichia coli , peptide sequence , gene expression , genome , linguistics , philosophy
The in vivo transcription start sites of the nah and sal operons of the NAH7 plasmid were determined by S1 nuclease mapping and the nucleotide sequence surrounding these transcription start sites was determined. Since expression of both of these operons is coordinately controlled by the product of the transcriptional activator gene nahR, the sequences were compared to locate potential sites involved in common regulation. In the 100-base-pair region preceding transcription start sites of both operons, three regions of extensive homology were found and may be involved in nahR-mediated transcriptional control: between -80 and -60 with 81% homology; between -40 and -28 with 75% homology; between -1 and +15 with 70% homology. Comparison of the promoter sequences of nah and sal with the analogous sequences of the xylABC and xylDEFG operons of the TOL plasmid showed little homology between the 5' regions of these two sets of positively regulated hydrocarbon degradation operons. In addition, the transcription start site of the nahR regulatory gene was located and its promoter sequence was determined. The nahR promoter overlapped at the -35 position of the sal promoter; however, the nahR gene is transcribed in the opposite direction. Sequences similar to the consensus sequences of Escherichia coli promoters (at -35 and -10) were found in nah, sal, and nahR at the appropriate positions.