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This document has been archived.

NSF Press Release


Embargoed until 2 P.M., EDT
NSF PR 00-54 - August 9, 2000

Media contact:

 Cheryl Dybas

 (703) 292-8070

Program contact:

 Eve Barak

 (703) 292-8442

This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

"Gatekeeper" Protein Is Key to Cellular Life

Researchers funded by the National Science Foundation (NSF) and affiliated with Ohio State University have determined that a seemingly ordinary protein called YidC found within the membranes of bacteria serves as a gatekeeper of sorts, allowing into the membranes other proteins essential for the bacteria to live. When YidC isn't present, the bacteria dies.

The finding surprised scientists who long believed that certain "independent" proteins were able to pass into membranes on their own. The new discovery, reported in this week's issue of the journal Nature, may suggest a completely new pathway for the translocation of proteins within basic biological units.

While YidC has been known to be present in cells for some time, researchers were unclear as to what role it might perform, explained Ross Dalbey, a chemist at Ohio State University. Dalbey and student James Samuelson were investigating the protein's role in Escherichia coli bacteria as part of an NSF-supported study. "The process of membrane insertion is needed for cellular respiration in bacteria and mitochondria, as well as for photosynthesis in chloroplasts," Dalbey said.

The researchers hope that uncovering the function of YidC and related proteins may offer new ways of either enhancing cell function or in accelerating cell death - two mechanisms essential in fighting most diseases. "In order to exploit cellular membranes through biotechnology for the benefit of mankind, we need first to understand the basic processes by which proteins are inserted into those membranes," explains Eve Barak, program director in NSF's division of molecular and cellular biosciences, which funded the research. "This research sheds important new light on this fundamental biological function."

More startling was the discovery that several other proteins that are remarkably similar to YidC may play similar roles inside mitochondria and in chloroplasts as well.

"Proteins are synthesized within the cytoplasm of the cell but they then have to be transported, or inserted, either across or into the membranes of organelles within the cell to do their work," Dalbey said. These membranes function as barriers, he said, blocking proteins and other compounds from areas where they don't belong.

In their work, Dalbey and Samuelson developed a strain of E. coli in which YidC can be depleted. They found that when the YidC was absent, proteins could not migrate into the membranes and the bacteria died.

They also looked at another specific protein called Procoat that was considered "independent," that is, researchers believed it would insert itself into the membrane on its own. But in bacteria lacking YidC, even the Procoat was blocked from entering the membrane. "To everyone's surprise, the protein nearly everybody thought inserted spontaneously requires YidC to succeed in entering the membrane," Dalbey said.




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