Using high-resolution X-ray crystallography, a team including William A. Cramer has determined the structure and surprising behavior of a protein receptor complex, or "gate," found in the outer membrane of an E. coli bacterium. The complex is one of thousands of such tiny gates that the cell uses to bring substances into its cytoplasm, or interior. The team also determined the structure of one such substance, a protein called colicin, that the gate admits into the E. coli, marking a first for the biological field.
"This represents the first time we have seen a receptor complex and its corresponding importable protein up close," said Cramer, who is Henry Koffler Distinguished Professor of Biological Sciences in Purdue's School
of Science. "While we have seen the gates before as a group, we have never
seen how an individual gate works to bring a protein inside. This information
could tell us a lot about our own metabolism."
The research, which appears in the November issue of Nature Structural Biology, was performed by a team including lead authors Genji Kurisu, Stanislav Zakharov and Masha Zhalnina. Also contributing was Michael Wiener of the University of Virginia's Department of Molecular Physiology and Biological Physics.
The group's work turned up some unusual details about cellular commerce, the business an E. coli cell conducts with the outside world through its membrane. With hundreds of protein receptors serving as gate guards, the membrane admits into the cytoplasm the nutrients the cell needs to exist. In most cases, receptors are made to admit only one particular substance.
"If you've ever seen the game 'Perfection,' in which you have to put a number of uniquely shaped pegs into their c
Contact: Chad Boutin