DNA's Cast of Thousands
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B UILDING ON THE DNA REVOLUTION academic ability, and to home in on that,” considerations are al- says Fuller. “There’s a history of people so gaining promi- ECTION with no qualifications who are now senior.” nence. For instance, S 25 years ago MRC Past as prologue didn’t bother to patent At the end of April, hundreds of former LMB Milstein’s technique researchers will converge on Cambridge to for making monoclon- PECIAL celebrate the 50th anniversary of Watson and al antibodies, now a S Crick’s DNA paper. They include numerous fundamental tool in Nobel laureates whose prizewinning research many industries. The came after their time at LMB, as well as same was true of prominent department heads, institute direc- Sanger’s sequencing tors, and journal editors. There is no doubt in technology. Today, their minds that LMB is unique. “I don’t patenting is encour- think if you had put the same people in a U.S. aged, says Henderson, institution that they would have done as and several compa- well,” says Rubin. Biological incubator. Hundreds of budding molecular biologists got nies, such as Celltech, But can it continue to be so special? their start at the Laboratory of Molecular Biology, opened in 1962. are associated with Thirty years ago, “the field was much the lab. smaller. It was the place for U.S. postdocs to To keep pace with the burgeoning sci- Klug and Henderson suspect that the go, and the best went,” Rubin explains. entists and staff—about 400, more than place is good for at least a couple of more “Now there are many good places.” Al- twice the number 30 years ago—the build- Nobels. Even today, with universities, though funds still flow relatively freely, pa- ing has doubled in size every decade since medical foundations, and other organiza- perwork, regulations, and other constraints 1962. A new building is in the works. Says tions working to create hotbeds of scien- have crept in, Henderson notes. And while Klug, “I am worried that we will get too tific creativity, LMB still earns strong ku- he and his colleagues pride themselves on big and lose the ethos on which the lab has dos. Says Yale’s Joan Steitz: “There have their small labs, which range in size from 1 been built.” been very good research institutions that to 10 people, they worry that they will fall LMB now relies on a glossy annual re- have tried to capture the flavor and spirit, behind. “There’s so much more you can do port rather than word of mouth to publi- but they haven’t got it.” with more manpower,” says Pelham. cize its accomplishments. Commercial –ELIZABETH PENNISI OF MOLECULAR BIOLOGY;AND SOCIETY MRC LABORATORY SCIENCE CREDITS: BOTTOM) TO (TOP LIBRARY PHOTO NEWS DNA’s Cast of Thousands Watson and Crick’s discovery revealed much, suggested more, but left many details unanswered. Ever since, researchers have been discovering the proteins that unlock DNA and the genetic code When James Watson and Francis Crick with proteins. But rebuilt today, Watson and elucidated the structure of DNA, they dis- Crick’s bare-bones model would be draped covered an elegantly simple molecule. with proteins that kink and curl, repair, and With cardboard cutouts, metal, and wire, otherwise animate DNA. they showed how DNA’s two chains wound around each other, with the paired bases DNA ascendant inside, one full rotation every 10 bases. The age of DNA began well before Crick Their model immediately suggested how and Watson were born. In the 1860s, Image not DNA copied itself and enabled genetic Friedrich Miescher, a Swiss working in information to flow from one generation Tübingen, Germany, isolated a strange, available for to the next. They boasted that they had phosphorus-rich material from the cell nu- online use. found the “secret of life”—essentially, bi- cleus. Within decades, it was clear that this ology’s master molecule that controlled peculiar substance—later identified as nu- the fate of the cell and, consequently, of cleic acids—was fundamental to the cell’s the organism. chemistry. Somehow. Fifty years of research since then has Throughout the early part of the 20th shown that, despite its precision design, this century, biochemists argued about DNA’s molecule can’t dance without a team of cho- role. Some postulated that it was the stuff of reographers. Like a puppet, DNA comes genes; others insisted that proteins carried alive only when numerous proteins pull its “strings.” At the time of their discovery, Naked DNA. Watson and Crick’s first model of Watson and Crick had only the haziest of DNA didn’t begin to reveal the complex set of ideas about how this double helix interacted proteins the molecule needs to do its job. 282 11 APRIL 2003 VOL 300 SCIENCE www.sciencemag.org B UILDING ON THE DNA REVOLUTION S PECIAL California Insti- errors, the cell calls in its molecular repairers. tute of Technolo- These enzymes mark the bad DNA, cut it gy in Pasadena out, and replace it with the right code. One of showed this to be the best-studied examples is that of bacteria S the case. as they recover from exposure to ultraviolet ECTION Shortly after- light. First, a complex of UvrABC proteins ward, Arthur Ko- recognizes the damage. Then the UvrABC rnberg of Stanford enzyme cuts at two sites a few bases to either University and his side of the defective DNA and whisks away colleagues dem- that piece. DNA polymerase then fills in the onstrated that an gap with the correct bases. enzyme they had discovered several DNA’s messenger years earlier or- Watson and Crick’s discovery left wide open chestrates the syn- the question of how DNA specifies which thesis of each new proteins are made. It was more than a DNA strand. The decade before the “code” itself was worked Chameleon. Although the B-DNA is most common and the one first described, enzyme, DNA out, along with all the intricate details of the certain conditions force this molecule into A- or Z-DNA configurations. polymerase, adds gene-to-protein transition. just the right nu- The first clues that genes specified the genetic code. Even though Oswald Av- cleotide base to the separated DNA strands, amino acids came from V. M. Ingram of the ery, Colin MacLeod, and Maclyn McCarty making sure the new one exactly matches its University of Cambridge. He of Rockefeller University in New York City template. More than 20 additional proteins studied the sickle cell trait, demonstrated in 1944 that DNA and not are also known to perform distinct func- in which two defective proteins carried the genetic code, the debate tions in copying DNA. Some help un- continued; even Crick and Watson at first wind DNA, for example; others mark First glimpse. This 84 (1996) disagreed on this point. the starting point of replication. And x-ray diffraction pat- CELL , Soon after Watson joined him at the Uni- since then researchers have found at tern hinted that DNA versity of Cambridge, U.K., in 1951, Crick least two more DNA polymerases: ET AL. was helical, thereby was persuaded. Across two continents, they one specializes in making new DNA; helping Watson and and others set out to discover just what another helps repair damaged DNA. Crick come up with DNA looked like. Tapping a newly devel- Some mistakes are introduced long the right structure. oped imaging technique called x-ray crystal- after DNA polymerase has finished its lography, Rosalind Franklin and Maurice job—for instance, when radiation or toxic genes can lead to severe ane- Wilkins of King’s College in London pro- chemicals cause the wrong base or bases to mia, while one causes just mild problems. In (1992) ; S. FROM ADAPTED KIM 9 6 duced images that showed DNA was heli- be substituted or others to be deleted al- 1957, he tracked the defect down to a single CELL cal. Others were busy envisioning together. This necessitates a amino acid change, a mistake in whatever ., how DNA’s bases were more extensive repair sys- specified the order of amino acids in the he- ET AL arranged to enable it to tem. Faced with such moglobin protein. The work suggested that function. Watson and DNA was that template. Crick’s discovery set- Duplicating DNA. The ring section of Then, in 1961, Marshall tled once and for all DNA polymerase helps this enzyme’s Nirenberg of the U.S. Na- that genes were core work more efficiently as it car- tional Institutes of Health in made of DNA. But ries out DNA replication. The crys- Bethesda, Maryland, real- it took eight more tal structure shows the ring (red ized that a three-base se- years—and the and yellow) sliding down the DNA. quence in DNA, UUU, spec- efforts of many ified the amino acid phenyl- researchers—to alanine; soon the rest of the crack the genetic triplets were deciphered. code contained in the We now know that DNA’s nucleotide bases. triplet code is transmitted Watson and Crick, par- through an intermediary ticularly Crick, had many ideas called messenger RNA STRYER, ED. (W. H.AND CO., FREEMAN 1995); JEREMY NORMAN; X-P KONG . ,L about how DNA worked, something (mRNA), a closely related, their landmark 1953 paper hinted at in its single-stranded nucleic acid. last sentence: “It has not escaped our notice The mRNA ferries this in- BIOCHEMISTRY that the specific pairing we have postulated formation out of the nucleus immediately suggests a possible copying to the ribosome, which mechanism for the genetic material.” The builds the protein one amino idea was that, as the double helix uncoiled, acid at a time.