Courtesy of Harry Noller/UC Santa Cruz

View Enlarged Image Protein Factory Ribosome structure reveals the system's molecular complexity. A tRNA (orange) is shown base pairing with part of mRNA (gold) in its center. Related Story Protein Factory Reveals Its Secrets Topics Covered

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Weizmann Institute Yonath

Yale University Steitz

MRC Ramakrishnan

The Royal Swedish Academy of Sciences today awarded the 2009 Nobel Prize in Chemistry to scientists in the U.S., England, and Israel "for studies of the structure and function of the ribosome," the protein-making factory of cells.

Structural biologists Venkatraman Ramakrishnan of the MRC Laboratory of Molecular Biology, Cambridge, U.K.; Thomas A. Steitz of Yale University; and Ada E. Yonath of Weizmann Institute of Science, Rehovot, Israel, will share the $1.4 million prize.

Several researchers—many more than three—have made key contributions in recent years to a better understanding of the structure and function of the ribosome, but advances achieved by the three awardees are among the most significant of those contributions. Ramakrishnan, Steitz, and Yonath have all used X-ray crystallography to map the ribosome's structure, and the resulting 3-D models have cast light on its complicated mechanism of action.

The ribosome is a huge protein-RNA complex that is essential to life. This macromolecular giant, which is composed of one small and one large subunit, reads mRNA messages transcribed from the genetic code in genomic DNA and translates them by catalyzing the biosynthesis of the proteins they encode. The bacterial ribosome in particular is the site of action for antibiotics such as aminoglycosides and tetracyclines and a key target for the design of new antibiotics as well.

Yonath, is professor of structural biology and director of the Helen & Milton A. Kimmelman Center for Biomolecular Structure & Assembly at the Weizmann Institute. Yonath, in collaboration with the late biochemist H. G. Wittmann of Max Planck Institute for Molecular Genetics, Berlin, was the first to obtain crystals of the ribosome, a prerequisite to the X-ray crystallographic studies honored with this year's prize. Later, she and her coworkers studied ribosome structure with cryo-crystallography, obtained X-ray crystal structures of the small and large subunits, revealed the binding sites of several antibiotics, and proposed modes of action for the drugs. She is an Israeli citizen.

The contributions of Steitz, professor of chemistry and of molecular biophysics & biochemistry and a Howard Hughes Medical Institute Investigator at Yale, have included a structure of the large subunit, obtained by a group led by him and his Yale colleague Peter B. Moore. This study helped show that the ribosome is actually a ribozyme (RNA-based enzyme) by revealing that RNA predominates in the active site. The group later determined structures of the large subunit bound to various substrates, such as antibiotics and transition-state analogs.

Ramakrishnan, now senior scientist and group leader at the Structural Studies Division of the MRC Laboratory for Molecular Biology, is a U.S. citizen born in India. His group's contributions have included determination of the crystal structure of the small subunit and a demonstration of how the ribosome discriminates between correct and incorrect tRNAs, which deliver specific amino acids to the ribosome for protein synthesis.

American Chemical Society President Thomas H. Lane commented that "the research behind these prizes shows how the transforming power of chemistry can improve peoples' lives. Scientists around the world are using the winners' research to develop new antibiotics that can be used in the ongoing battle against antibiotic-resistant microbes that cause so much illness, suffering, and death."