This gene codes for the ferrochelatase, the enzyme which catalyzes the incorporation of ferrous iron into protoporphyrin IX, the intermediate precursor of protoheme. B. abortus hemH codes for a 352 amino acid protein that is 70% and 58% identical to M. loti and B. japonicum hemH, respectively. In
B. japonicum ferrochelatase is essential for normal nodule development. Mutants in this gene incited nodules on soybean that did not fix nitrogen, contained few viable bacteria and did not express leghemoglobin heme apoprotein. B. abortus hemH null mutants are avirulent in mice, conserved the ability to invade the cells but have lost the capacity to multiply inside them.
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