U.S. study points to strong new class of antibiotics

CHICAGO (Reuters) - Three naturally occurring antibacterial compounds hold promise for a new class of antibiotics, offering hope for fresh weapons against infection at a time when older drugs are losing their punch, researchers said on Thursday.

The new agents, reported in the journal Cell, may even provide a quicker cure for tuberculosis, which could help people stick to the prescribed therapy better and reduce the development of resistant strains.

“The three antibiotics are attractive candidates for development as broad spectrum antibacterial agents,” said Richard Ebright of Rutgers University in New Brunswick, New Jersey.

Ebright and colleagues showed how the three antibiotic compounds -- myxopyronin, corallopyronin and ripostatin -- block the action of bacterial RNA polymerase, an enzyme needed by bacteria to unlock genetic information from DNA needed to make proteins.

Blocking this enzyme kills the bacteria, they said.

All three compounds are naturally produced by some bacteria for use in a kind of chemical warfare against other bacteria. The agents work by taking advantage of a design flaw in bacterial RNA polymerase.

“RNA polymerase has a shape reminiscent of a crab claw, with two prominent pincer-like projections,” Ebright said in a statement.

“Just as with a real crab claw, one pincer stays fixed and one pincer moves -- opening and closing to keep DNA in place.”

All three antibiotics work by jamming the pincer hinge, keeping the bacteria from letting DNA into the enzyme. Without the needed genetic code, the bacteria cannot make proteins.

This understanding has allowed the researchers to find ways to tinker with the chemical structure of the antibiotic targets to make them even more potent.

The compounds appear to work against a broad range of bacteria, including the bacteria that causes tuberculosis, which infects about a third of the world’s population.

Current TB drugs known as rifamycins also act on RNA polymerase, but they do it in a different way.

“As a result, these antibiotics can function simultaneously with rifamycins and can be co-administered with rifamycins for more rapid clearance of infection,” Ebright said.

Reporting by Julie Steenhuysen, editing by Will Dunham