Aerobactin: A Multifaceted Siderophore.

Abstract

Different bacteria produce different iron(III) chelating small molecules called siderophores to fetch iron(III) from the surrounding environment. Aerobactin is a hydroxamate siderophore discovered in Aerobacter aerogenes in 1969. Aerobactin synthesizing and importing proteins are encoded by iuc-iutA operon which was found to confer growth advantage in pColV bearing pathogenic strains of Escherichia coli in case of human and animal infections. Being an important virulence factor in pathogenic Escherichia, Shigella, Klebsiella and Yersinia, aerobactin export and import mediating proteins like ShiF and IutA respectively as well as its synthesizing enzymes are potential therapeutic targets. Aerobactin encoding machinery can be horizontally transferred to many other bacteria leading to niche diversification of pathogens. So, keeping track of its spread is medically very important. Knowledge about different regulators of aerobactin expression helps to further diversify the therapeutic approaches. Iron sequestration function of aerobactin is used by different bacteria for competition in the environment, formation of multicellular structures like swarming colonies and biofilm as well as predation. Suitable modification and conjugation of aerobactin may lead to potential beneficial applications. Unfortunately, this area is far less developed in aerobactin compared to other siderophores. Progress in development of specific inhibitors for different steps of aerobactin synthesis is wanted. Also, development of sensitive, easy to handle inhibitor assay methods are needed. Hence, it is important to draw attention to the different aspects of this siderophore. So, using data from several published literatures, this review is discussing aerobactin from its synthesis, regulation of expression, functions in different bacteria, ways of potential modifications and future directions of this field.