"The results are all consistent with the same conclusion: In contrast to half a century of prior study and the textbook-classic model, amphotericin kills yeast by simply binding ergosterol," Burke said.
"The beauty is, because we now know this is the key mechanism, we can focus squarely on that goal. Now we can start to think about drug discovery programs targeting lipid binding."
The researchers currently are working to synthesize a derivative that will bind to ergosterol in yeast cells, but will not bind to cholesterol in human cells, to see if that could kill an infection without harming the patient. They also hope to explore other derivatives that would target lipids in fungi, bacteria and other microbes that are not present in human cells. Attacking these lipids could be a therapeutic strategy that may defy resistance.
In addition to exploiting amphotericin's lipid-binding properties for antimicrobial drugs, Burke and his group hope to harness its channel-creating ability to develop treatments for conditions caused by ion-channel deficiencies; for example, cystic fibrosis. These new findings suggest that the ion-channel mechanism could be decoupled from the cell-killing mechanism, thus enabling development of derivatives that could serve as "molecular prosthetics," replacing missing proteins in cell membranes with small-molecule surrogates.
"Now we have a road map to take ampho-terrible and turn it into ampho-terrific," Burke said.
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign