Promoter mapping and transcriptional regulation of the iron-regulated Neisseria gonorrhoeae fbpA gene.

In this study, we have mapped the promoter region of the Neisseria gonorrhoeae ferric iron binding protein-encoding gene fbpA, determined the start point of transcription, and examined the accumulation of fbpA mRNA Primer extension analysis of the fbpA promoter region indicated a single transcriptional start site located 51 bp upstream of the ATG translational start site. Northern blot analysis with a 200-bp fbpA structural gene probe detected one transcript of 1.0 kb in RNAs extracted from gonococcal cultures grown under iron-restricted conditions; the 1.0-kb transcript was observed to accumulate at a steady rate throughout the growth cycle. In comparison, in cultures grown under iron-sufficient conditions, the intensity of the 1.0-kb transcript was reduced considerably. Isolation of total RNA from rifampin-treated cells indicated that the half-life of the 1.0-kb fbpA transcript in cells grown under iron-restricted conditions was 1.2 +/- 0.2 min, while that of the 1.0-kb fbpA transcript obtained from cultures grown under iron-sufficient conditions was 0.5 +/- 0.1 min. Taken together, our results indicate that the fbpA promoter is regulated by iron and that transcription and translation of FbpA are closely linked.