And this is where they found the single-nucleotide polymorphisms (or SNPs, pronounced "snips"), which were more common in the isolates collected from patients with infections related to their heart implants.
To further test the effects of these SNPs, the team used a supercomputer to simulate the formation of the bond between the bacterial and human proteins. When they plugged standard amino acid sequences from each protein into the supercomputer, the molecules maintained a distance from each other. When they altered the sequence of three amino acids in the bacterial surface protein and entered that data, hydrogen bonds formed between the bacterial and human proteins.
"We changed the amino acids to resemble the SNPs found in the Staph that came from cardiac device-infected patients," Lower said. "So the SNPs seem to have a relationship to whether a bond forms or not."
Fibronectin-binding protein A is just one of about 10 of these types of molecules on the Staph surface that can form bonds with proteins on host cells, Lower noted. And it's also possible that fibronectin, the human protein on the other side of the bond studied so far, might contain genetic variants that contribute to the problem as well.
What the scientists do know is that bacteria will do all they can to survive, so it won't be easy to outsmart them.
"Bacteria obey Charles Darwin's law of natural selection and can evolve genetic capabilities to allow them to live in the presence of antibiotics," Lower said. "Most physicists would tell you there are certain laws of physics that dictate what happens and when it happens, and you can't evade or evolve ways around those. If you understand the basic physics of it, can you exploit a fundame
|Contact: Steven Lower|
Ohio State University