Article #3 Cool Boomerangs

• Primitive earth – no oxygen – favored the existence of iron in a soluble state that is easily taken up by the bacteria 

  Oxygen-rich environment – convert iron into an unsoluble state
• Ancient bacteria - iron unavailability
• Iron – important in microbial metabolism; hence they evolved sophisticated and highly efficient mechanisms for ensuring that the optimum supply of iron is acquired.
• Siderophores (iron carriers) - captures iron to bacterial cells via specific receptors on the surface of bacteria
• E. coli - has seven sets of genes for siderophore iron transport systems
• Some host cells may strike back by releasing a protein called lipocalin or siderocalin which captures and strips iron from bacterial siderophores!
• Magnetotactic Bacteria - takes up large amount of iron (200x than E. coli)
• Iron assimilation - entails highly efficient and meticulous metering out of iron uptake
• Magnetotactic bacteria have several sets of iron uptake systems and a shut-off mechanism through a protein called ferric uptake regulator (Fur) which acts as a traffic enforcer regulating the influx of iron to avoid the toxic effects of too much iron. 
• Tadashi Matsunaga

  • shown that if magnetotactic bacteria are grown in a high-iron medium, most of the iron is taken up and is used for magnet formation
  • Remaining iron in and outside of cell (low levels) trigger siderophore production
• With high iron supply, magnetotactic bacteria express genes to take up large amounts of iron to form magnetic particles, thus starving themselves of the element. At the onset of this iron starvation, enter the siderophores.
• Thalassemia

  • iron-overload disorder
  • Treatment
  • infusion of a purified fungal siderophore called desferrioxamine (DFO) which works by collecting excess iron in the body and eventually flushing it out with the feces and urine. 
• Trojan Horse Principle

  • eliminate effects of hit-and-miss targeting in drug delivery systems, scientists have come up with the idea of precise targeting by using this operation-penetration scheme
  • The strategy entails purifying or synthesizing an analogue of the pathogen’s native siderophore and attaching it with an antibiotic.