RirA, an iron-responsive regulator in the symbiotic bacterium Rhizobium leguminosarum

Jonathan D. Todd, Margaret Wexler, Gary Sawers, Kay H. Yeoman, Philip S. Poole, Andrew W. B. Johnston

Research output: Contribution to journalArticlepeer-review

102 Citations (Scopus)


Mutations in a Rhizobium leguminosarum gene, rirA (rhizobial iron regulator), caused high-level, constitutive expression of at least eight operons whose transcription is normally Fe-responsive and whose products are involved in the synthesis or uptake of siderophores, or in the uptake of haem or of other iron sources. Close homologues of RirA exist in other rhizobia and in the pathogen Brucella; many other bacteria have deduced proteins with more limited sequence similarity. None of these homologues had been implicated in Fe-mediated gene regulation. Transcription of rirA itself is about twofold higher in cells grown in Fe-replete than in Fe-deficient growth media. Mutations in rirA reduced growth rates in Fe-replete and -depleted medium, but did not appear to affect symbiotic N fixation.
Original languageEnglish
Pages (from-to)4059-4071
Number of pages13
Issue number12
Publication statusPublished - 1 Dec 2003

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