Feb 12, 2013 (4 years and 4 months ago)


S10 Microbial siderophore mediated transport
Guenther Winkelmann
Microbiology & Biotechnology, University of Tuebingen,
Auf der Morgenstelle 28, 72076 Tuebingen, Germany
Significant advances have been made on the transport of iron
mediated by siderophores in microbes. This process involves the
biosynthesis, regulation, excretion and recognition of siderophores
by membrane located transport systems. To date we know approxi-
mately 200 different siderophores which can be grouped into
different families according to their ligand types, such as cate-
cholates, hydroxamates, carboxylates and mixed-type siderophores.
Although iron-regulated biosynthesis is a characteristic feature of all
microbial siderophores, only few biosynthetic pathways have been
analyzed in detail. The Gram-negative enterobacteria and
Pseudomonads, as well as Bacillus, Staphylococcus and some
ascomycetous fungi (Yeast, Neurospora, Aspergillus) have been
characterized in depth with regard to binding proteins and transport
mechanisms. Many transport proteins for siderophores have been
identified, characterized and its crystal structure solved, but it is
largely unknown how the various siderophores are recognized and
transported to the inside. Another question is how and where, iron
release takes place. Cleavage of the ligand or subsequent excretion
seem to be essential biochemical reactions to complete siderophore
mediated uptake of iron. Thus, several topics will be addressed in
this review: 1) The structural diversity, 2) biosynthesis and
regulation, 3) transport mechanisms, 4) specificity and recognition
and 5) iron release mechanisms.