Nobel 2006: Kornberg relied on SLAC expertise and technology
BY MITZI BAKER
The transcription process visualized in Kornberg’s X-ray crystallography studies. The protein chain shown in grey is RNA polymerase.
Roger Kornberg's Nobel Prize-winning determination of the structure of RNA polymerase has been described as a "technical tour de force." The key to the visualization of this fundamental biological molecule in action was synchrotron radiation, supplied by the powerful X-ray crystallography instruments at the Stanford Synchrotron Radiation Laboratory.
Visible light rays are longer than the dimensions of the atoms that make up a protein molecule, but the wavelength of X-rays can be just the right size. The problem is that X-rays of the type generated in hospitals are not intense enough to observe molecules at the atomic level.
In the 1970s, scientists at SSRL and other laboratories realized they could harness synchrotron radiation—once considered to be an annoying byproduct of particle accelerators—to provide the intensity needed to reveal the structures of complex molecules. Synchotron X-rays are millions of times brighter than conventional X-rays.
"This work could not have been done without synchotron radiation," said Kornberg. SSRL, which is one of five centers supplying synchrotron X-rays in the United States, is located at the Stanford Linear Accelerator Center. In the late 1990s, the SSRL made a special effort to develop instrumentation and make it available quickly, allowing Kornberg's group to begin collecting data. That timing proved to be critical for the group's groundbreaking 2000 and 2001 Science papers outlining the basic structure of RNA polymerase.
"There was an appreciation for the possible significance of the work, so we got particular help from SSRL," said Kornberg, who received his PhD in chemistry from Stanford.
"We are very pleased that the magnificent structural work of Roger Kornberg and his colleagues was significantly enabled by synchrotron X-rays at SSRL," said SLAC deputy director Keith Hodgson, PhD. He noted that early next year, SSRL will have a new instrument that will be 10 to 100 times brighter yet.
Kornberg's group has additionally benefited from a robotic screening system, launched by SSRL in 2003. It significantly cuts down the painstaking process of locating the one in a hundred crystals that are suitable for analysis by X-ray crystallography.
"We were one of the first guinea pigs for the SSRL robotics," said Dave Bushnell, PhD, a research associate who has worked with Kornberg for 13 years. "We were very happy because we can sit there and sip coffee while the robot does in five hours what used to take two of us 24 hours."
