Insights into the chemistry of the amphibactin–metal (M(3+)) interaction and its role in antibiotic resistance

We have studied the diversity and specificity of interactions of amphibactin produced by Vibrio genus bacterium (Vibrio sp. HC0601C5) with iron and various metal ions in + 3 oxidation state in an octahedral (O(h)) environment. To survive in the iron-deficient environment of their host, pathogenic bacteria have devised various efficient iron acquisition strategies. One such strategy involves the production of low molecular weight peptides called siderophores, which have a strong affinity and specificity to chelate Fe(3+) and can thus facilitate uptake of this metal in order to ensure iron requirements. The Fe uptake by amphibactin and the release of iron inside the cell have been studied. Comparison of the interaction of different transition metal ions (M(3+)) with amphibactin has been studied and it reveals that Co and Ga form stable complexes with this siderophore. The competition of Co and Ga with Fe impedes iron uptake by bacteria, thereby preventing infection.