



The paper describes the co-crystal structure of two parts of the three-part efflux pump that recognizes and removes heavy metal toxins from bacteria. A research team led by Yu - an Iowa State associate professor of physics and astronomy, of chemistry, of biochemistry, biophysics and molecular biology and an associate of the U.S. Department of Energy's Ames Laboratory - is working to discover the assembled structure of the entire three-part efflux pump.


"These pumps have to assemble together in order to pump out heavy metals and antibiotics," Yu said. "Researchers may be able to use these findings to design an inhibitor so the pump can't be assembled and can't work."

Yu and his research team described the first part of the pump - the inner membrane transporter known as CusA - in the Sept. 23, 2010, issue of the journal Nature.

The current paper describes the inner membrane transporter and how it interacts with the pump's middle adapter, known as CusB. The two parts together are known as the CusBA complex.




The studies revealed, molecule by molecule, how the inner transporter's three molecules bind and interact with the middle adaptor's six molecules. The studies also revealed the adaptors' six molecules form a funnel-like channel extending from the top of the transporter.

The researchers used those discoveries to predict how the three-molecule structure of the pump's third part, the outer membrane channel known as CusC, interacts with the CusBA complex.

