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BIOCHEMISTRY
In the latest in a series of stunning advances, a team of structural biologists has unveiled the most comprehensive view yet of one of the cell's most critical components: the ribosome.
While DNA carries instructions for building proteins, ribosomes actually do the work. They produce proteins by stitching together amino acids carried in by transfer RNA (tRNA), according to instructions transmitted from DNA in the nucleus by messenger RNA. Biologists have long wondered just how this factory churns out the thousands of different proteins necessary for life.
Now, as reported online this week in Science (www.sciencexpress.org), a team led by Harry Noller at the University of California, Santa Cruz (UCSC), presents a molecular view of a complete bacterial ribosome, describing its structure down to 5.5 angstrom resolution. Although that resolution is not high enough to discern the positions of individual atoms in this giant complex of proteins and RNA-which means that more work needs to be done to verify the new analysis-it "represents a huge step forward," says Peter Moore, a Yale biochemist.
Over the past few years, Moore and others have obtained progressively more detailed structures of the two major components, called subunits, of the ribosome. Moore, with Yale's Thomas Steitz and their colleagues, recently published the highest resolution structure yet of the large subunit (Science, 11 August 2000, p. 905). But Noller's team is the first to provide a detailed view of the entire molecule. (The group produced a blurrier image, at roughly 7.8 angstrom resolution, in 1999.) Thanks to this new work, researchers can now see "how the two...