Scientists isolate molecule that helps produce proteins

Tuesday, February 15, 2011

WASHINGTON - Scientists have isolated a molecular assistant called Spy that helps bugs produce proteins for medical and industrial purposes.

Bacteria are widely used to manufacture proteins used in medicine and industry, but the bugs often bungle the job.

Many proteins fall apart and get cut up inside the bacteria before they can be harvested or collapse into useless tangles instead of folding properly, as they must in order to function normally, the Nature Structural & Molecular Biology journal reports.

A research team led by James Bardwell, professor of molecular, cellular and developmental biology and of biological chemistry, at the University of Michigan, developed a way to coerce bacteria into making large quantities of stable, functional proteins.

Then, in exploring why these designer bacteria were so successful, the scientists discovered the molecular helper, Spy, according to a Michigan statement.

Further study showed that the cradle-shaped Spy aids in protein refolding and protects unstable proteins from being cut up or sticking to other proteins.

In the first phase, the team designed biosensors that directly link protein stability to the antibiotic resistance of bacteria.

When an unstable protein is inserted into the middle of the biosensor in a bacterium, it disrupts the bug’s resistance to antibiotics. When the protein is stabilized, resistance is restored.

The researchers inserted a particularly unstable protein into E. coli, which forced the bacteria to either adapt by improving protein stability or die when exposed to antibiotics.

Through a “directed evolution” experiment, the team generated designer bacteria that produced up to 700 times more of the previously unstable protein.

“It is exciting to realize that if even bacteria are asked in the right way, they can come up with good solutions to hard problems,” said postdoctoral fellow Shu Quan, who spearheaded the work.

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