Get the red. staph bacteria steal heme and iron trap, eliminating red color.
In war zones around the world, bandits steal food intended for starving civilians. One of the most feared pathogens medicine performs the same kind of piracy, new research suggests. To obtain the iron it needs to keep the bacteria Staphylococcus aureus steals the essential mineral from human blood cells. The chemicals that stop the crime could offer a new type large need antibiotics to kill dangerous infections resistant to drugs.
S. aureus causes diseases ranging from ear infections to meningitis. Antibiotics that kill it quickly lose their punch. Half of all hospital-acquired staph infections now resist all but one antibiotic, vancomycin. Some strains learn to avoid even one, so that new ways to kill the bug are urgently needed.
Nutrition is a possible weak point. S. aureus , like other bacterial pathogens and like us, needs iron to keep its engines running. There are a few years, a team led by Olaf Schneewind, now of the University of Chicago, hungry S. aureus for iron and took one of its proteins in the act. The protein had caught a chemical containing iron called heme in hemoglobin, the protein that makes red blood cells red
Now the postdoc Schneewind Eric Skaar has unraveled a conspiracy between this protein and six other that allows the microbe pilfer iron human red blood cells. Collectively, these proteins are known as surface determinants iron-regulated, or ISD proteins. After S. aureus hole punches protein in the red blood cell, Isd proteins form a bucket brigade flying heme in hemoglobin and pries out of his iron to feed the bacteria, Skaar, Schneewind and colleagues report in the 7 February science . They also identified two other proteins called sortases Isd proteins that bind to the cell wall so they can do their job. This means that drugs that block the way, perhaps by blocking sortases could prevent even the most wicked S. aureus strains to get the iron they need to grow, says Skaar.
"I liked [the study] much," said Klaus Hantke microbiologist at the University of Tübingen in Germany, adding that it offers the best description yet of how a bug extract iron from heme. But S. aureus and other microbes have backup plans for iron, he warns, to block flying heme iron may not kill them.
Related Sites
Backgrounder on antibiotic resistance
Centers for prevention pages S Disease Control. aureus , which are resistant to two common antibiotics, methicillin and vancomycin
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