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Arthur Kornberg (1918–2007)

2007; Elsevier BV; Volume: 28; Issue: 4 Linguagem: Inglês

10.1016/j.molcel.2007.11.004

1097-4164

Peter Burgers,

Biochemical and Molecular Research

Arthur Kornberg, one of the most distinguished and influential biochemists of his generation, died October 26. He was 89 years old, and until the end he remained fascinated with basic biochemical research. This year saw three papers from his lab describing advances in the field of polyphosphate metabolism, which had been his main research interest in the last 15 years. Arthur was born in Brooklyn on March 3, 1918. He obtained his MD degree from the University of Rochester in 1941 and spent the next few years at the then fledgling research institute of the NIH studying the relationship between vitamins and health. But soon after World War II ended, he became more and more interested in the study of enzymes. Enzymology was an emerging science and Arthur set out to train in the premier enzymology labs. He spent a year with Severo Ochoa at New York University Medical School studying enzymes of the citric acid cycle. Over a decade later, in 1959, Arthur would share the Nobel Prize with Ochoa “for their discovery of the mechanisms in the biological synthesis of ribonucleic acid and deoxyribonucleic acid.” Both scientists initiated their investigations long after the time Arthur spent in Ochoa's lab. This initial training was followed by a fellowship in 1947 with Carl and Gerti Cori at Washington University School of Medicine. Here, he studied enzymes in nucleotide coenzyme metabolism. At that time, the Cori lab was the place to be for biochemical research. Ochoa himself had trained there, as well as Luis Leloir, who would later be awarded the Nobel prize in Chemistry for his discovery of the building blocks for carbohydrate biosynthesis. In 1953, at the urging of Cori, Arthur returned to Washington University to become chairman of the Department of Microbiology. In St. Louis, Arthur continued his research on nucleotide metabolism, which turned out to be a prerequisite for attacking the problem of DNA synthesis in the test tube. It allowed him to make 14C-labeled dTTP for his explorations into DNA synthesis with extracts made from E. coli. The first success was marginal but encouraging and was published as a two-page “birth announcement” in 1956 (Bessman et al., 1956Bessman M.J. Kornberg A. Lehman I.R. Simms E.S. Enzymic synthesis of deoxyribonucleic acid.Biochim. Biophys. Acta. 1956; 21: 197-198Crossref PubMed Scopus (97) Google Scholar). In this communication he writes: “Polymerization of TTP requires ATP, a heat stable DNA fragment(s), provisionally regarded as a primer, and two enzyme fractions.” One of the enzyme fractions contained the DNA polymerase, while the other fraction contained a mixture of nucleases and nucleotide kinases that degraded the added DNA to mononucleotides and recycled them into the other three precursor dNTPs, hence the additional requirement for ATP as an energy source. Looking back at the discovery of the DNA polymerase, one might naturally have assumed that DNA was added to the enzyme reaction to serve as a template primer, but this was not the case. Despite the determination of the structure of double-stranded DNA a few years earlier by Watson and Crick and their suggestion of templated synthesis, albeit by spontaneous self-assembly, Arthur was more influenced by the work of Carl and Gerti Cori on carbohydrate metabolism (Kornberg, 1989Kornberg A. For the Love of Enzymes. The Odyssey of a Biochemist. Harvard University Press, Cambridge, MA1989Google Scholar). The Coris had shown that glycogen phosphorylase uses an oligosaccharide primer for polymerization, and Arthur saw some analogies between that system and polynucleotide synthesis. Thus, DNA was added as a primer for polynucleotide synthesis and secondarily, to protect the newly synthesized radioactive DNA against degradation by nucleases. The notion that an enzyme would rely on its substrate to receive instructions for catalysis was inconceivable at the time. However, that this must indeed be the case soon became apparent. Within a year, research in the Kornberg lab had progressed tremendously, with the substantial purification of DNA polymerase I and of the four individual dNTPs (Lehman et al., 1958Lehman I.R. Bessman M.J. Simms E.S. Kornberg A. Enzymatic synthesis of deoxyribonucleic acid. I. Preparation of substrates and partial purification of an enzyme from Escherichia coli.J. Biol. Chem. 1958; 233: 163-170Abstract Full Text PDF PubMed Google Scholar). The critical importance of this latter advance is often overlooked, but in two papers published in JBC in 1958, the Kornberg lab not only described the first synthesis of the three remaining dNTPs but also showed for the first time that deoxynucleoside 5′ triphosphates functioned as actual precursors for DNA synthesis. Yet another discovery, which could only be made with pure reagents at hand, was that substantial DNA synthesis required the addition of all four dNTPs. To Arthur, these results immediately suggested “the hypothesis that the added DNA is serving as a primer and template and that extensive synthesis of DNA chains is possible only when all the complementary deoxynucleotides are available for polymerization. This speculation is attractive because it is consistent with what would be expected if this enzyme were responsible for the synthesis of a self-duplicating molecule” (Bessman et al., 1958Bessman M.J. Lehman I.R. Simms E.S. Kornberg A. Enzymatic synthesis of deoxyribonucleic acid. II. General properties of the reaction.J. Biol. Chem. 1958; 233: 171-177Abstract Full Text PDF PubMed Google Scholar). When these groundbreaking papers were first submitted to JBC in the fall of 1957, they were rejected because of a dispute in semantics. One of the reviewers objected to the name “DNA” as the product of enzymatic synthesis, because Kornberg had not shown his enzymatic product to have genetic activity. They insisted it be called “polydeoxyribonucleotide” instead. Fortunately, with a change of JBC editorship to John Edsall, the papers were accepted and appeared in 1958. It would take another decade before biochemical synthesis of DNA with demonstrated genetic activity was realized. When it became apparent in 1969 that DNA polymerase I was not the replicative DNA polymerase, aspersions were cast on the importance of Kornberg's discoveries and even on the general mechanism of DNA polymerization that was established by his studies of DNA polymerase I. Nothing was further from the truth! All the principles that mediate faithful recognition and replication of the DNA template that were illuminated by the study of DNA polymerase I are conserved in the enzymes that function in chromosomal DNA replication. In fact, the debate regarding the replicative versus repair functions of DNA polymerases still continues today, particularly in more complex eukaryotic organisms. In the summer of 1959, Kornberg left St. Louis to set up the Biochemistry Department at the newly established Stanford Medical School in Palo Alto. Three months later, he was awarded the Nobel prize for Medicine. Arthur took most of the Microbiology faculty with him to Stanford. This included Bob Lehman, Paul Berg, Mel Cohn, Dale Kaiser, and David Hogness. Together, these scientists would form the brilliant core of the Biochemistry Department that propelled it into world renown. Trained as an organic chemist at the State University in Leiden, I first became exposed to enzymology when I studied the stereochemistry of replication by DNA polymerase I in Fritz Eckstein's lab at the Max Planck Institute in Göttingen. Fascinated by DNA replication and its enzymology, I joined Kornberg's lab in the spring of 1980 to learn enzymology. Mixing labs with students working for different investigators was a practice that Kornberg had initiated when he set up the Biochemistry Department. The lab I worked in was shared between Kornberg and Lehman students. Thus, I also became familiar with the exciting new recombination studies carried out in the Lehman lab and had a first-row seat as Bob's students were teasing out the fascinating properties of the E. coli recA protein. Before joining the Kornberg lab, I had been warned by several people that Arthur was a slave driver, a general opinion held as far away from Stanford as Germany. Indeed, Arthur demanded that his people be just as committed to research as he himself was. Interestingly, this call for commitment did not translate into the demand for long nights and weekends spent in the lab, although many of us did. Rather, he demanded that scientific discovery and the pursuit of new ideas was foremost in our mind. Because of this demand for commitment and excellence, the weekly group meetings were feared in the Kornberg lab, for not only would the data be put under intense scrutiny, but also its importance would be questioned as well. At one of these meetings, when a postdoc was describing a particularly mundane aspect of his study of a replication protein, Arthur asked him why he was interested in this. “Because some day this information could be useful,” was the postdoc's answer. Arthur retorted: “I'm not interested in making bricks that somebody could use to build a castle; I want to build the castle!” However, he could also energize his people. One day, when my own studies were not progressing very well, Arthur walked into the lab. For a minute he stood still, intently looking at my lab bench. Then he gently stroked his hand over it and said, “Reji Okazaki worked at this bench; he did some wonderful things at this bench,” and then he left. Reji Okazaki was the renowned Japanese scientist who in 1967 proposed the semidiscontinuous model for DNA replication that explained how antiparallel DNA could be coordinately replicated by DNA polymerases. Reji and his wife, Tuneko, trained in Arthur's lab in the early 60s. Arthur's message was clear, I should strive to follow Okazaki's example. Kornberg always retained an affinity for Washington University. It was at his urging that I applied for a position in the Biochemistry Department. And he would come back for occasional visits. The last one was in September of 2004 when the Cori laboratory in the Biochemistry Department was dedicated as a National Historic Landmark by the American Chemical Society. At that time, he discussed his “Ten Commandments for Enzymology” (Kornberg, 2000Kornberg A. Ten commandments: lessons from the enzymology of DNA replication.J. Bacteriol. 2000; 182: 3613-3618Crossref PubMed Scopus (76) Google Scholar). Over the years, some of these commandments would change as his own research changed. However, among the constant ones was: “Thou shalt not waste clean thinking on dirty enzymes!” which he attributed to Ephraim Racker. Many of the problems that have plagued biochemical analysis in the past, and still do, can be attributed to the breaking of this commandment. Sometimes he referred to the following as the 11th commandment: “Thou shalt support basic research!” Kornberg's belief in the value of fundamental research and his commitment to federal support for it remained unwavering throughout his life. In a 1996 letter to Science, he urged continued Federal support for fundamental scientific research (Kornberg, 1996Kornberg A. Funding basic research.Science. 1996; 273: 857-858Crossref Google Scholar): “I can document that throughout the history of medical science the major advances in diagnosis, treatment, and prevention of disease were based on the curiosity of biologists, chemists, and physicists unrelated to the ultimate applications of this basic knowledge to the development of drugs and devices.” He contrasted this with translational research: “In sharp contrast to the success of investments in basic research are the disappointments in narrowly directed programs, such as the assault on cancer, in which the complexity of the problem far exceeds the essential available knowledge.” These words were written in 1996 when federal research support was less scarce than it currently is. Today, the call for support of translational research at the cost of basic research may be even stronger. Arthur's work in DNA synthesis is a shining example of how the interest in pure scientific research, the drive to understand how cellular molecular machineries work, and how the machineries can be reconstituted and manipulated in the test tube has led to enormous technical advances. Arthur's presence as a researcher and as a champion for basic research will be sorely missed.