Animation: John Rueter, Portland State University RIBOSOMES, made up of two subunits (gray and violet), ride along threads of messenger or mRNA (yellow), translating genetic information (above). Codons--stretches of three bases--on the mRNA are matched up with complementary anticodons on transfer RNAs (green and pink), thereby forming the polypeptide chains (navy squares) used to build proteins. New detailed images of ribosomes (below) have revealed how the three binding sites for tRNAs (green, pink and blue) act as a conveyor belt, as well as other mechanical aspects of protein formation. Image: CATE et. al.

The latest pictures of ribosomes may not be the most arresting biological images--but they represent a giant leap forward in the refinement of X-ray crystallography and in understanding a fundamental puzzle in molecular biology: how these tiny organelles, like highly efficient factories, manufacture all of the proteins for sustaining life from simple genetic templates. The new results, says researcher Jamie Cate of the Whitehead Institute "show where different pieces of equipment are on the shop floor."

Two papers in the September 24th issue of Science describe the images--the first to resolve an entire ribosome to 7.8 angstroms. The longer paper, by Harry F. Noller of the University of California, Santa Cruz, his colleagues Marat Yusupov and wife Gulnara Yusupova, Cate and Thomas Earnest of the Lawrence Berkeley National Laboratory, presents the structure of the ribosome and its interaction with several molecules. The second, by Noller, Yusupov, Yusopova, Cate and Gloria Culver of Iowa State University, details connections within the ribosome.

These reports follow two others in Science and Nature in August, which outlined different aspects of the ribosome's structure. But this recent flurry of results comes after some three decades of little progress. The ribosome--three RNA strands and 54 proteins woven into two separate, but entangled lumps--has not been an easy knot to unravel; its form has proved as hard to figure out as its function.

Ada Yonath of the Weizmann Institute of Science and Max Plank Institute for Molecular Genetics, who also has new results yet to be published, began trying to create images of the ribosomes structure in the late 1970s. She revealed her first success at crystallizing the organelle and using X-ray diffraction to produce an image at a meeting in 1980--pictures which garnered little enthusiasm from colleagues. Still, a few prominent mentors, such as Nobelist Sir John Kendrew, encouraged her, and in 1981, she made crystals that produced diffraction patterns clear enough to distinguish atoms in parts of the structure that were only 3 angstroms apart.

Achieving the same resolution for the entire ribosome presented new problems. But following Yonath's lead, other researchers were confident it could be done. Among them were Yusupov and Yusupova, who met as graduate students at the Protein Research Institute in Pushchino, Russia. Together they generated ribosome crystals by 1987, but did not have access to X-ray beamlines. So in 1996 they joined forces with Noller, who had been studying the biochemistry of ribosomes for 30 years, at UCSC. The team recruited crystallographer Cate and enlisted the help of Earnest, director of the crystallography facility at LBNL--one of the few places offering a synchrotron capable of producing X-rays with enough energy to create images of something as large as a ribosome.

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1. 1. wu yi 01:35 PM 9/4/09

   they would build yes, but they'll be stable for the cause of the experament. (for the need) but they wouuln't accept new data

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