FIG. 1.

Exochelin biosynthesis locus. Nine ORFs were identified in cosmid pYUB563. Based on homologies to known biosynthesis and transport genes, the ORFs were named fxbA, orf1, orf2, fxbB, fxbC, fxuD, orf3, orf4, and orf5. Six of these ORFs and the previously identified putative iron uptake genes fxuC, fxuA, and fxuB which are located in the 3′ end of the fxbA gene are likely involved with exochelin biosynthesis and transport pathways. PFe→, the putative iron box with direction of transcription is indicated. The transcription of fxbA gene and the orf1, orf2, fxbB, and fxbC gene operon were under the control of divergent promoters and iron boxes.