Bradyrhizobium japonicum senses iron through the status of haem to regulate iron homeostasis and metabolism

Summary The Irr protein from the bacterium Bradyrhizobium japonicum is expressed under iron limitation to mediate iron control of haem biosynthesis. The regulatory input to Irr is the status of haem and its precursors iron and protoporphyrin at the site of haem synthesis. Here, we show that Irr controls the expression of iron transport genes and many other iron‐regulated genes not directly involved in haem synthesis. Irr is both a positive and...