Molecular evolution

How bacteria and host fight for iron

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A study of primate and bacterial proteins involved in capturing iron from the blood has revealed an evolutionary arms race in the battle over this important nutrient.

Matthew Barber and Nels Elde at the University of Utah in Salt Lake City focused on transferrin, a protein that transports iron from the blood into cells. Pathogenic bacteria compete for this mineral by using their own protein, called TbpA, to bind transferrin. The researchers sequenced transferrin from 21 primate species to trace its 40-million-year evolutionary history, and tested the molecules' interactions with TbpA from two common human pathogens. They found specific amino-acid changes in a rapidly evolving region of transferrin that prevent TbpA from binding to it.

They also pinpointed transferrin-binding sites in TbpA that are genetically diversifying under selection, showing how competition for a nutrient can drive primate and pathogen evolution.

Science 346, 13621366 (2014)

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