A History of Iron Metabolism in the Mycobacteria - Iron Acquisition by the Genus Mycobacterium - page 3

Chapter 2
A History of Iron Metabolism
in the Mycobacteria
Colin Ratledge
“Mycobacteria are nothing more than E. coli wrapped up in a
fur coat”—Frank Winder.
Abstract The importance of iron to the metabolism of the mycobacteria was
gradually appreciated during the first half of the last century. Frank Winder
working in Dublin in the 1950s and 1960s was the first to establish the absolute
amounts of iron needed for growth and, from his work, it was then possible to
investigate the consequences of iron deficiency and subsequently how iron was
solubilized and transported into mycobacterial cells. Parallel with this work, was
the discovery by Alan Snow, at ICI Ltd, UK, of the mycobactins. These are essen-
tial growth factors for Mycobacterium paratuberculosis and their role in iron
binding was then pivotal to elucidating the main aspects of iron uptake. However,
mycobactins, being wholly intracellular materials, were unable to act as external
siderophores for the solubilization of iron; this role was then found to be carried
out by the exochelins discovered by the author of this review. The exochelins were
of two types: those from the non-pathogenic mycobacteria were water-soluble
pentapeptides whereas those from pathogenic species were modifications of myco-
bactin and were then named as the carboxymycobactins. The interdependency of
these materials and others is then unraveled in this review. The review focuses
mainly on the research work carried out over the last century leaving the present
work on iron uptake to be covered in other reviews in this monograph.
Keywords Carboxymycobactin • Exochelin • Iron acquisition • Mycobacterial
siderophores • Mycobactin
C. Ratledge ( * )
Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK
e-mail: [e-mail]