This month marks the 65th anniversary of James Watson and Francis Crick's groundbreaking paper in Nature, where they elegantly described the double helical structure of DNA. To celebrate, we take a look at the men behind the discovery and give a brief account of their work.
Who Was Watson?
James Dewey Watson was born in Chicago on 6th April 1928 to parents of English, Scottish and Irish descent. While his early interests centered on bird biology, Watson had a change of heart in his late teens and swiftly steered his career ambitions towards the study of genetics.
After obtaining a Bachelor of Science in zoology from the University of Chicago (1947), Watson pursued graduate studies at Indiana University, where he was awarded his PhD in 1950. He conducted his PhD studies under the supervision of Italian Nobel Laureate Salvador Luria, who shared the Nobel Prize in Physiology or Medicine with Max Delbruck and Alfred Hershey in 1969 for their groundbreaking discoveries about viral replication and genetic structure.
Watson later conducted postdoctoral studies at the University of Copenhagen, Denmark, where he studied bacteriophage nucleic acid synthesis with biochemist Herman Kalckar. One year later, he began working with Danish microbial physiologist Ole Maaloe, with the clear goal to determine whether DNA or protein was the genetic material behind phage infection of bacteria. Although this work proved inconclusive, Watson's interest in the structure of DNA intensified, and he became convinced by advances in the field that DNA had a definite molecular structure that could be unravelled through X-ray diffraction.
In 1951, Watson relocated to England to work on the molecular structure of DNA. Sir John Cowdery Kendrew, English biochemist, crystallographer and Nobel Laureate was instrumental in arranging Watson's postdoctoral work in England. Together with Max Perutz, John Kendrew shared the 1962 Nobel Prize in Chemistry for determining the first atomic structures of proteins via X-ray crystallography.
Francis Crick was born on the 8th June 1916 to English parents in a small village near Northampton, England. Crick took a shine to science from an early age, and he performed his first scientific experiments with his uncle in a small shed at the end of his uncle's garden.
After excelling in scientific subjects in school, Crick earned a Bachelor of Science in physics from University College London (1937). He then initiated PhD studies, also at University College London, but was forced to stop during WWII. During the war, Crick worked with many notable scientists at the Admiralty Research Laboratory in London, where he made significant contributions to the design of a new type of mine that was effective against German minesweepers. He later finished his PhD and conducted postdoctoral studies at the Polytechnic Institute of Brooklyn.
After WWII, Crick began his career in biology in 1947, aged 31. Crick is reported to have described his transition from physics to biology as if one were being born again.
In the years that followed, Crick studied the physical properties of cytoplasm under the supervision of Honor Bridget Fell (Cambridge's Strangeways Laboratory), and he later joined the Cavendish Laboratory under the direction of Sir Lawrence Bragg to work alongside Max Perutz and John Kendrew. Bragg, who won a Nobel Prize at the age of 25, was on a mission to elucidate the structure of DNA. The Cavendish Laboratory was in steep competition with researchers at the King's College London, a fact that eventually led to the meeting and development of a close friendship between Crick and James Watson.
The Double Helix is Solved!
Watson and Crick started working together in 1951 in the Cavendish laboratory, and using the critical X-ray diffraction results of Rosalind Franklin and Raymond Gosling (Franklin's graduate student) at King's College London, the pair later developed a model for the helical structure of DNA.
The duo's three-dimensional, double-helical model for the structure of DNA also relied heavily on the earlier findings of Erwin Chargaff, who found that the amount of adenine and cytosine in DNA is equal to the amount of thymine and guanine, respectively. They pair also made use of 3D model building techniques based on known molecular distances and bond angles, which had been advanced by American biochemist, Linus Pauling. Linus Pauling actually proposed an incorrect model for DNA's structure just months before Watson and Crick's submission to Nature.
To arrive at their final model, Watson and Crick played around with cardboard cutouts that represented DNA's 4 bases and subunits of other nucleotides, and having been stuck for some time, they were eventually able to move forward with input from American scientist Jerry Donohue, whom they had met at Cambridge University. Donohue suggested that the pair create new cardboard cutouts to reflect recently published calculations about the structure of guanine that would likely be more accurate than their original cutouts. Within days of Donohue's suggestion, the double helix was solved.
Watson and Crick received Franklin's and Gosling's X-ray diffraction results from Gosling and Franklin's colleague Wilkins, and in 1962, they were jointly awarded the Nobel Prize in Physiology or Medicine for their work, along with Wilkins. Franklin died in 1958 and despite her significant contributions to the double helix discovery, she could not be awarded the Novel prize posthumously.
Standing on the Shoulders of Giants
Although Watson and Crick are often considered to be behind the discovery of DNA, this is not the case. They were however the first to accurately describe the double-helical structure of DNA. It must not be forgotten though that their work would not have been possible without the prior findings of many other researchers, such as the Swiss physician and biologist Friedrich Miescher, who was the first to isolate nucleic acids, the American biochemist Phoebus Levene who characterized the structure and bases that make up both DNA and RNA, and Austro-Hungarian biochemist Erwin Chargaff, whose fundamental studies on the relative amounts of adenine, thymine, guanine and cytosine in DNA suggested that DNA, and not protein, was the hereditary material.
Almost 7 decades on, few would disagree that the duo's discovery marked the dawn of a new era in biology, representing a crucial turning point in our ability to understand and probe life, with DNA sequencing and gene editing strategies now dominating the fields of genetics and medicine.
Pray, L. (2008) Discovery of DNA structure and function: Watson and Crick. Nature Education 1(1):100. For an account of the research findings that paved the way for Watson and Crick's discovery.
The Francis Crick Papers. A collection of papers about Francis Crick's biography and career, provided by the U.S. National Library of Medicine.
The James Watson Papers. From Archives at Cold Spring Harbour Laboratory.