... and of thekanamycin insertion mutant nirF strain(SBN03) in the upper right panel. Growth of SBN11 (DnirF) is shown in the bottom leftpanel and of SBN13 (DnirF) containingpEG276-nirF in the ... d1heme.Replacement of an equivalent His, His41, in NirF byAla abolished binding of the heme to the protein.Known distal heme -binding residues, such as Met, Lysor Cys [18,19], were substituted for His41 in ... conserved N-terminal Gly-rich(GXGX2GX7G) motif in all NirF sequences, which issuggestive of a binding to a nucleotide-containingcofactor. This motif has also been found in severalother...