Cornell University researchers, who are trying to understand how proteins evolve and function by looking at their structural features, have uncovered the crystal structure of a protein involved in making the building blocks of DNA correctly.
The protein is AIRs kinase, and to the researchers' surprise, its shape is similar to other members of the riboside kinase family, proteins that are important in making DNA and RNA, the molecules that make up genes. As a result, the research group now has nine members of the riboside kinase family that are thought to have evolved from a common protein ancestor.
Writing in a recent issue of the journal Structure , Steven Ealick, professor of chemistry and chemical biology, and his graduate student Yan Zhang report that revealing the structure of AIRs kinase is another step in deciphering what proteins look like, a major goal of the National Institutes of Health, which funds the Ealick research group's work.
"Often, two proteins with the same function have no sequence similarity," says Ealick, whose research group works with crystallized proteins, the building blocks of all living organisms, and has solved 50 protein structures over the past 20 years. "From knowing the genetic sequence alone, we wouldn't necessarily guess that two proteins play a similar role in an organism."
Zhang took just two months of "trial and error" -- an unusually short time -- to get the AIRs kinase protein to crystallize. Then, using the Northeastern Collaborative Access Team (NE-CAT) beamline at the Advanced Photon Source at Argonne National Laboratory and the Cornell High Energy Synchrotron Source, two of only five sources of high-energy X-ray beams, she obtained the protein's "optical transform," the intermediate stage between the crystal and the ultimate model of the structure.