Genomics of iron uptake.

Iron is essential for growth in most bacteria due to its redox activity and its role in essential metabolic reactions; it is a cofactor for many bacterial enzymes. The bacterium is a multidrug-resistant nosocomial pathogen. responds to low iron availability imposed by the host through the exploitation of multiple iron-acquisition strategies, which are likely to deliver iron to the cell under a variety of environmental conditions, including human and animal infection. To date, six different gene clusters for active iron uptake have been described in , encoding protein systems involved in (i) ferrous iron uptake (); (ii) haem uptake ( and ); and (iii) synthesis and transport of the baumannoferrin(s) (), acinetobactin (/) and fimsbactin(s) () siderophores. Here we describe the structure, distribution and phylogeny of iron-uptake gene clusters among >1000 genotypically diverse isolates, showing that , , and / clusters are very prevalent across the dataset, whereas the additional haem-uptake system is only present in a portion of the dataset and the gene cluster is very rare. Since the expression of multiple iron-uptake clusters can be linked to virulence, the presence of the additional haem-uptake system may have contributed to the success of some clones.