"We were amazed when we knocked out GlgE that we saw this DNA damage response," says Dr. Jacobs. "That's usually a very effective way to kill bacteria, when you start damaging the DNA."
The researchers discovered a second way of killing TB after observing a crucial connection between their novel alpha glucan pathway and a second pathway that also synthesizes alpha glucans.
When the researchers knocked out one of the other enzymes in their novel pathway, the pathway's shutdown didn't kill the bacteria; similarly, inactivating an enzyme called Rv3032 in the second alpha glucan pathway failed to kill the microbes. But inactivating both of those enzymes caused what the researchers term synthetic lethality: two inactivations that separately were nonlethal but together cause bacterial death.
"The bacteria that cause TB need to synthesize alpha glucans," notes Dr. Jacobs. "And from the bacterial point of view, you can't knock out both of these alpha glucan pathways simultaneously or you're dead. So if we were to make drugs against GlgE and Rv3032, the combination would be extremely potent. And since TB bacteria need both of those alpha glucan pathways to live, it's very unlikely that this combination therapy would leave behind surviving bacteria that could develop into resistant strains."
Dr. Jacobs adds that findings from this study could also enhance treatment of diseases caused by other species of mycobacteria. Leprosy, for example, which still occurs in the U.S. and other countries, is caused by a mycobacterium related to TB. Treating leprosy now involves using several different drugs, some of which are also used to treat tuberculosis.
|Contact: Deirdre Branley|
Albert Einstein College of Medicine