October 7, 2009

Seminal Work for 2009 Nobel Prize in Chemistry Conducted at NSLS

Two of this year's three recipients of the Nobel Prize in Chemistry conducted much of their award-winning research at the Brookhaven National Laboratory's National Synchrotron Light Source (NSLS).

Thomas Steitz

Venkatraman Ramakrishnan

Venkatraman Ramakrishnan, a former employee in Brookhaven's biology department and long-time user of the NSLS, now at the Medical Research Council Laboratory of Molecular Biology in Cambridge, and Thomas A. Steitz of Yale University, also a long-time NSLS user, share the prize with Ada E. Yonath of the Weizmann Institute of Science "for studies of the structure and function of the ribosome."

Ribosomes make the thousands of proteins that are required for the structure and function of each living cell. Specifically, the ribosome translates the genetic instructions encoded by DNA into chains of amino acids that make up proteins. The ribosome is composed of two subunits: 30S, which reads the code; and 50S, which links up the amino acids.

Starting in the late 1990s, both Ramakrishnan and Steitz used a technique called x-ray crystallography at the NSLS to gather atomic-level structures of these two ribosome subunits, Ramakrishnan on 30S and Steitz on 50S. In this technique, scientists analyze how a beam of powerful x-rays is scattered by molecules arranged in a crystal to determine the positions of the molecule's individual atoms.

Ramakrishnan began his work on ribosomes while employed in Brookhaven's biology department from 1983 to 1997, first at the High Flux Beam Reactor and later at the NSLS. Even after leaving the lab for the University of Utah, he used the NSLS to collect crystallography data that contributed directly to his Nobel Prize. In 1999, his research at NSLS beamlines, especially X25, resulted in the first report of a low-resolution structure of the 30S subunit¹. In 2000, Ramakrishnan helped uncover the high-resolution version of the structure², which was based on data from the NSLS, the Advanced Photon Source (APS) at Argonne National Laboratory, and the European Synchrotron Radiation Facility.

The structure of the 30S subunit on the cover of the September 2000 edition of Nature.

The structure of the 50S subunit.

"The 30S ribosome subunit experiments were indeed a tour de force," said Lonny Berman, an NSLS physicist and spokesperson for beamline X25. "As Venki remarked to me at that time, the 30S subunit crystals did not diffract very well, and moreover, were quite susceptible to radiation damage. Therefore, even with use of a beamline as bright as X25, data collected from many samples had to be merged together in order to form a composite data set."

At about the same time, Steitz worked with Brookhaven's biology department to collect NSLS data on the 50S subunit. The first low-resolution structures were solved in 1998³ and 1999⁴ using NSLS beamlines X12B and X12C. In 2000, Steitz' team presented the first high-resolution structure of 50S subunit using data from NSLS beamlines X12B and X25 and from the APS⁵.

"We were lucky to have been only a ferryboat-ride away from Yale so we could help with this project from the beginning," said Bob Sweet, a Brookhaven biophysicist and the leader of the group that runs NSLS beamline X25. "The skill, patience, and intuition of the Steitz group was remarkable, displayed in many visits. To watch this structure gradually reveal itself as their work bore fruit was a scientific experience of a lifetime."

These studies map ribosome functionality at the most basic, atomic level – providing information that is a spring board for these and many other researchers to more detailed investigations. The structures of 30S and 50S have been crucial to understanding everything from how the ribosome achieves its amazing precision to how different antibiotics bind to the ribosome, knowledge that could help researchers come to grips with the problem of multiresistant bacteria.

Support for operation of all three of the NSLS beamlines used in this seminal work came from the U.S. Department of Energy's Office of Biological and Environmental Research and the National Institutes of Health's National Center for Research Resources. DOE's Office of Basic Energy Sciences also provides support for the operation of beamline X25 as well as for the NSLS in general.

For more information, go to http://nobelprize.org/nobel_prizes/chemistry/laureates/2009/.

¹Clemons, W.M., Jr., May, J.L., Wimberly, B.T., McCutcheon, J.P., Capel, M.S., and Ramakrishnan, V., "Structure of a bacterial 30S ribosomal subunit at 5.5 A resolution," Nature 400, 833-840 (1999).

²Wimberly, B.T., Brodersen, D.E., Clemons, W.M., Jr., Morgan-Warren, R.J., Carter, A.P., Vonrhein, C., Hartsch, T., and Ramakrishnan, V., "Structure of the 30S ribosomal subunit," Nature, 407, 327-339 (2000).

³Ban, N., Freeborn, B., Nissen, P., Penczek, P., Grassucci, R.A., Sweet, R., Frank, J., Moore, P.B., and Steitz, T.A., "A 9 A resolution X-ray crystallographic map of the large ribosomal subunit." Cell 93, 1105-1115 (1998).

⁴Ban, N., Nissen, P., Hansen, J., Capel, M., Moore, P.B., and Steitz, T.A., "Placement of protein and RNA structures into a 5 A-resolution map of the 50S ribosomal subunit," Nature, 400, 841-847 (1999).

⁵Ban, N., Nissen, P., Hansen, J., Moore, P.B., and Steitz, T.A. "The complete atomic structure of the large ribosomal subunit at 2.4 A resolution," Science, 289, 905-920 (2000).