U.S. sweeps science Nobels

WASHINGTON — Roger Kornberg, a biochemist at Stanford University, won the Nobel Prize in chemistry Wednesday for figuring out the intricate way in which information in the DNA of a gene is copied in order to provide the instructions for building and running a living cell.

This "transcription" process, which is a cross between a waltz and a wrestling match on the molecular level, is essential for organisms as simple as yeast and as complex as human beings. It allows a cell to select the genes it needs from the thousands it doesn't, and to extract information from them efficiently and accurately.

Kornberg's prize completed an American sweep of the science prizes for physiology or medicine, physics, and chemistry. That has occurred only twice before, in 1946 and 1976.

Kornberg, 59, also becomes the seventh winner with a parent who won a Nobel. His father, Arthur, shared the 1959 Nobel medicine prize for studies of how genetic information is transferred from one DNA molecule to another.

"Transcription is key to reading the information that is in our genes. His work allowed us to look in snapshots at how transcription works, and to look in beautiful detail," said Jacqueline Barton, a nucleic-acid chemist at the California Institute of Technology.

Kornberg's work is unusual in that it bridges three fields — biochemistry, biophysics and X-ray crystallography — that are each difficult and consuming.

"What sets Roger apart from every other researcher in the area is the fact that he was willing and able to put together every way of looking at the transcription system to obtain answers," said Francisco Asturias, a cell biologist at the Scripps Research Institute in La Jolla, Calif.

Kornberg's discovery has no immediate medical applications but is crucial to unlocking the medical promise of stem cells and of understanding diseases, such as cancer, that occur when the transcription process goes awry.

Organisms more complicated than bacteria store their genes in a nucleus, a compartment apart from the rest of the cell's machinery. These so-called eukaryotic cells are faced with a fundamental problem.

They carry thousands of genes — in the case of human beings, about 30,000 — that together provide the instructions to make all the parts of all cells. But beyond the first few days of embryonic life, no cell needs all those instructions. It needs only a few hundred, or at most a few thousand. But it needs to be able to get to them quickly.

But efficient retrieval — finding a single tool in a garage, or a single book in a library — is only the beginning of the problem. The gene cannot be taken out of the nucleus, like a tool or a book. Instead, the information in it has to be copied. The copy is then sent to a distant part of the cell, where it is "translated" into a specific protein, the desired end-product.

The information in genes is encoded in DNA, which has a twisted, two-strand structure. The copy that leaves the nucleus is made of RNA, which has a single strand. Both DNA and RNA are built of letterlike units, nucleotides, strung end-to-end. The RNA copy is made by separating the two strands of DNA and then using one strand as a letter-for-letter template to make the RNA strand.

The thing that does this is a giant enzyme called DNA polymerase II, which finds a gene and makes an RNA message through a series of actions that include feeling, unfolding, sorting, shoving and releasing.

Kornberg's feat was to show how those steps occur on a physical, three-dimensional, nonmetaphorical basis.

On Monday, the medicine prize went to Americans Andrew Fire and Craig Mello for discovering a powerful way to turn off the effect of specific genes, opening a potential new avenue for fighting diseases as diverse as cancer and AIDS.

On Tuesday, Americans John Mather and George Smoot won the physics prize for work that helped cement the big-bang theory of how the universe was created.

The economics prize will be announced Monday and the peace prize on Oct. 13. A date for the literature prize has not been set.

Material from The Associated Press and Los Angeles Times is included in this report.