Attack and Counterattack Documented Through Evolutionary Time (IMAGE)
Caption
When bacteria that cause infectious diseases invade, the host starves the bacteria by hiding circulating iron, an essential nutrient it needs for survival, within the folds of a protein called transferrin. When the bacterial protein, TbpA, grasps hold of the primate protein, transferrin, it can steal transferrin's iron. Plotted on the primate family tree, transferrin has evolved mutations (green circles, green arrow points to most recent mutation) over evolutionary time that allow transferrin to evade TbpA. Plotted on a bacterial family tree, TbpA, in turn, has evolved mutations (blue circles, blue arrows points to most recent mutation) that again enable it to grasp hold of transferrin and steal it's iron. The evolutionary arms race has lasted 40 million years, highlighting the importance of the primate defense mechanism, called nutritional immunity, in the conflict between host and bacterial pathogen.
Credit
Janet Iwasa, Ph.D., University of Utah
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Credit Janet Iwasa, Ph.D., University of Utah
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