Roger Kornberg lecture

Roger David Kornberg (born April 24, 1947) is an American biochemist and professor of structural biology at Stanford University School of Medicine.

Kornberg was awarded the Nobel Prize in Chemistry in 2006 for his studies of the process by which genetic information from DNA is copied to RNA, "the molecular basis of eukaryotic transcription." His father, Arthur Kornberg, who was also a professor at Stanford University, was awarded the Nobel Prize in Physiology or Medicine in 1959.

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Scientific Discoveries and Nobel Prize

All organisms are controlled by their genes, which are coded by DNA, which is copied to RNA, which creates proteins, which are sequences of amino acids. DNA resides in the nucleus. When a cell expresses a gene, it copies (transcribes) that gene's DNA sequence onto a messenger RNA (mRNA) sequence. mRNA is transported out of the nucleus to ribosomes. The ribosomes read the mRNA and translate the code into the right amino acid sequence to make that gene's protein.

The DNA is transcribed to mRNA by an enzyme, RNA polymerase II, with the help of many other proteins. Using yeast, Kornberg identified the role of RNA polymerase II and other proteins in transcribing DNA, and he created three-dimensional images of the protein cluster using X-ray crystallography. Polymerase II is used by all organisms with nuclei, including humans, to transcribe DNA.

Kornberg and his research group have made several fundamental discoveries concerning the mechanisms and regulation of eukaryotic transcription. While a postdoctoral fellow working with Aaron Klug and Francis Crick at the MRC in the 1970s, Kornberg discovered the nucleosome as the basic protein complex packaging chromosomal DNA in the nucleus of eukaryotic cells (chromosomal DNA is often termed "Chromatin" when it is bound to proteins in this manner, reflecting Walther Flemming's discovery that certain structures within the cell nucleus would absorb dyes and become visible under a microscope).Within the nucleosome, Kornberg found that roughly 200 bp of DNA are wrapped around an octamer of histone proteins.

Kornberg's research group at Stanford later succeeded in the development of a faithful transcription system from baker's yeast, a simple unicellular eukaryote, which they then used to isolate in a purified form all of the several dozen proteins required for the transcription process. Through the work of Kornberg and others, it has become clear that these protein components are remarkably conserved across the full spectrum of eukaryotes, from yeast to human cells.

Using this system, Kornberg made the major discovery that transmission of gene regulatory signals to the RNA polymerase machinery is accomplished by an additional protein complex that they dubbed Mediator. As noted by the Nobel Prize committee, "the great complexity of eukaryotic organisms is actually enabled by the fine interplay between tissue-specific substances, enhancers in the DNA and Mediator. The discovery of Mediator is therefore a true milestone in the understanding of the transcription process."

At the same as Kornberg was pursuing these biochemical studies of the transcription process, he devoted two decades to the development of methods to visualize the atomic structure of RNA polymerase and its associated protein components. Initially, Kornberg took advantage of expertise with lipid membranes gained from his graduate studies to devise a technique for the formation of two-dimensional protein crystals on lipid bilayers. These 2D crystals could then be analyzed using electron microscopy to derive low-resolution images of the protein's structure. Eventually, Kornberg was able to use X-ray crystallography to solve the 3-dimensional structure of RNA polymerase at atomic resolution. The structure of RNA polymerase obtained by Kornberg is the most complex protein structure solved to date. He has recently extended these studies to obtain structural images of RNA polymerase associated with accessory proteins.[8]Through these studies, Kornberg has created an actual picture of how transcription works at a molecular level. According to the Nobel Prize committee, "the truly revolutionary aspect of the picture Kornberg has created is that it captures the process of transcription in full flow. What we see is an RNA-strand being constructed, and hence the exact positions of the DNA, polymerase and RNA during this process."

In 1959, Roger Kornberg's father, Arthur Kornberg, received the Nobel Prize in Physiology or Medicine for studies of how genetic information is transferred from one DNA molecule to another in a process called DNA replication. Specifically, Arthur Kornberg isolated the first enzyme capable of synthesizing DNA, bacterial DNA polymerase I, which was then the first known enzyme to take its instructions from a template, thus ensuring the conservation of genetic information during cellular growth and division. Roger Kornberg's younger brother, Thomas Bill Kornberg, discovered DNA polymerases II and III in 1970 and is now a geneticist at the University of California, San Francisco. All three Kornbergs have thus worked to understand how genetic information is put to use in cells. Roger and Arthur Kornberg are the sixth father-son pair to win Nobel Prizes.


Roger D. Kornberg. (2009, January 21). In Wikipedia, The Free Encyclopedia. Retrieved 05:03, February 24, 2009, from http://en.wikipedia.org/w/index.php?title=Roger_D._Kornberg&oldid=265517564