"Also, it's hard to believe that one cell's evolution could be based on what a whole bunch of cells do," said Brinker. "When we instead consider that an individual cell will do what's best for it, we can more clearly understand the benefits of that cell's behavior."
A bacterium may live longer by reprogramming itself to produce toxins or enzymes that allow it to access external nutrients, the Brinker group showed.
One aspect of experimental rigor was the team's ability to organize living cells into a nanostructured matrix. "We've already done this with yeast," said Brinker. "We just extended the process to bacteria."
A key question was whether a cell could distinguish between peptides emitted by itself from those sent by other cells. If signaling peptides were chemically the same, what would it matter which bacterium emitted it?
As it turned out, said Brinker, "Peptides could bond to surface receptors on their own [generating] cell. So a single cell's peptide molecules could activate its own genes to express proteins that make staph virulent."
Indicating that the experiment had isolated the actual cause of the transformation, when the number of peptides produced by a cell ultimately came to exceed the number of lippoprotein molecules in solution, a stalled "quorum-sensing" procedure started up again.
When still more signaling molecules were added to the mix, the cell's transformation occurred more rapidly.
Researchers hope to find a mechanism to locate bacteria reprogramming
|Contact: Neal Singer|
DOE/Sandia National Laboratories