100th Birth Anniversary of the Unsung Hero of DNA Double Helix

This year marks the 100^th anniversary of the birth on 25^th July 1920 of Rosalind Franklin, whose pivotal contribution to the discovery of the structure of DNA has been increasingly recognized since her untimely death from ovarian cancer at the age of 37 in 1958. There is now a general consensus that, if she had lived longer, she would have deserved to be the among three awardees of the 1962 Nobel prize in Physiology or medicine. Each Nobel prize can be bestowed on a maximum of three people and is never awarded posthumously. The prize went to Francis Crick, James Watson, and Maurice Wilkins for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material. However, the debates still rage on as to whether, given the climate at the time, she would have been included instead of one of the three awardees.

Rosalind Franklin
(courtecy: en.wikipedia.org)

On 1951 she got a three-year Turner and Natwell fellowship at King’s College, London to work under John Randall on proteins in solution and changes in their structure when they are heated or dehydrated, causing them to denature. However just before she arrived, Randall suddenly changed her project to the investigation of some DNA fibers that Maurice Wilkins, also working at King’s college with Randall.  Randall wrote to Franklin that ‘…this means that as far as the experimental X-ray effort is concerned there will be at the moment only yourself and Gosling…’. Unfortunately, Randall neglected to tell Wilkins about this new arrangement, even though Wilkins and Ray Gosling had already obtained good X-ray diffraction patterns from the DNA fibers. This set the scene for difficulties between Wilkins and Franklin which quickly escalated over the first six months of 1951 while Franklin was building new equipment to control the humidity of the DNA fibers using hydrogen gas bubbling through different salts.

The situation between Franklin and Wilkins reached such an impasse that, in October 1951, Randall directed Franklin and Gosling to work on the A (dehydrated) form of DNA fibers from Signer and the best X-ray camera, and Wilkins to work on the B (hydrated) form with some other fibers that did not crystallize well. Photo 51 was taken by Franklin and Gosling in May 1952 using a micro camera, and was the clearest photo yet obtained, but it was of the B form (92% humidity) on which they were not supposed to be working, so it was put away. The X-ray generator was a prototype fine focus device built at Birkbeck by Werner and Walter Spear which had been given to Wilkins and Gosling, but was then used solely by Franklin and Gosling.

Photo 51

By January 1953, Wilkins, who in turn, unknown to Franklin, showed photo 51 to James Watson when he visited King’s from Cambridge. Watson was working there with Francis Crick on building a model of DNA with newly obtained permission from W. L. Brag, the head of Cavendish Laboratory.

Cavendish Laboratory of Cambridge University
(source: atomicheritage.org)

On the 9th February 1953, FC and JW were shown RF's December 1952 MRC Review Committee report by Max Perutz. This report was not marked confidential, but the results in it were unpublished. It gave the space group of the A form DNA as face-centred monoclinic (C2), and specified the unit-cell dimensions and angles. FC realised that this space group gave a vital clue as to the structure, because it meant that the DNA looked the same both ways up, so that it must consist of two antiparallel helical chains, not three chains as some had postulated. Erwin Chargaff had already found that in DNA the number of adenines (A) + guanines (G) was equal to the number of thymines (T) + cytosines (C), and also that the numbers of A and T were the same, as well as the numbers of G and C. Another critical piece of the puzzle was solved when Jerry Donohue, a postdoc who shared an office with the model builders and was watching them at work, suggested that the bases were the keto and not the enol forms that they had been trying to use.
By 7th March 1953, FC and JW had built a model that seemed to fit with all the known information. Each purine (A, G) was paired with a pyrimidine (T, C) across the inside of the double helix formed by two antiparallel carbon-phosphate backbones. Wilkins went to see it on 12th March and told everyone at King's about it on his return. RF was about to leave King's where she was miserable and felt she could no longer work in the same environment as Wilkins. She and Gosling had already sent off two papers on the structure of the A form and had almost finished one on the B form, of which she was very near to having the structure. How much RF ever knew about which of her results were shown to whom and when they were shown, remains a matter of current debate.

Coins in memory of Franklin

Rosalind has received much belated posthumous recognition that sadly she did not live to witness, with at least 39 buildings or projects named after her, including the 2019 European Space Agency's ExoMars rover. Newnham College, Cambridge have named a student residential building, there is a blue plaque on the house in London where she lived from 1951 to 1958, in 2000 King's College named their new Dental Education Centre the Franklin-Wilkins Building (a painfully ironic coupling of names), and in 2018 the Rosalind Franklin Institute was launched at the Harwell Campus in Oxfordshire as an autonomous medical research centre under the joint venture of 10 universities, and funded by UK Research and Innovation. Beyond the UK, among others there is the Rosalind Franklin University of Medicine and Science in Chicago.
In 2017, under the Planning Act of 1990, Historic England listed her tomb as of `special architectural or historic interest', with the official description (which sums up the her scientific impact very well): `the tomb commemorates the life and achievements of Rosalind Franklin, a scientist of exceptional distinction, whose pioneering work helped lay the foundations of molecular biology; Franklin's X-ray observation of DNA contributed to the discovery of its helical structure'.
Notably, last year the University of Portsmouth announced that on 2nd September it was changing the name of its James Watson Halls to Rosalind Franklin Halls. Perhaps this act shows in microcosm the growing appreciation of the impact of Franklin's life and work, somewhat redressing the balance in the previous mis-allocation of credit.
By Zavizah.

Ref: https://journals.iucr.org/d/issues/2020/07/00/me6088/index.html