Abstract
A mutation was isolated in the Rhizobium leguminosarum gene fhuA, which appears to specify the outer-membrane receptor for the siderophore vicibactin. The mutant was defective in iron uptake and accumulated the siderophore vicibactin in the extracellular medium. Expression of fhuA was regulated by Fe3+, transcription being higher in iron-depleted cells. Transcription of fhuA was independent of a functional copy of rpol, a neighbouring gene that specifies a putative ECF sigma factor of RNA polymerase and which is involved in siderophore production in Rhizobium. Mutations in fhuA did not detectably affect symbiotic N2 fixation on peas. An fhuA::gus fusion was expressed by bacteria in the meristematic zone of pea nodules but not in mature bacteroids. Some other strains of R. leguminosarum also contain a pseudogene version of fhuA. The sequences of some of these and the 'real' fhuA genes were determined.
Original language | English |
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Pages (from-to) | 829-837 |
Number of pages | 9 |
Journal | Microbiology |
Volume | 146 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1 Apr 2000 |
Keywords
- ECF
- σ factor
- fhu genes
- Iron-medicated regulation
- Pseudogene
- Rhiozbia
- Siderophores