Nobel Chemistry Blog
(Inside Science Currents) -- During the announcement of the 2015 Nobel Prize in chemistry early this morning, the presenters from the Nobel committee rattled off some amazing numbers on DNA repair.
Shortly after the winners were announced, Sara Snogerup Linse, chair of the Nobel Committee for chemistry, unveiled a simplified model of the DNA molecule. The model of the double helix contained 22 pairs of letters, or bases. In reality, she said, this fragment is only 8 nanometers, or billionths of a meter long. But every cell contains 100 million times as much genetic information, so this would stretch out to 2 meters.
"It contains the recipes to make all the proteins needed to build you and make you function," said Linse.
Then she dropped an amazing number:
"If I were to pull out the DNA from a human body and place it in one row, it would cover the distance from the Earth to the sun and back 250 times." That puts even the length of a space elevator to shame!
Claes Gustafsson, another member of Nobel Committee on chemistry, talked about how well cells repair damage to DNA.
When DNA is copied, or replicated, an incorrect base is introduced approximately every one in a million times, he said. Since DNA gets copied whenever cells divide—and cell division has been estimated to occur in the body 50 to 70 billion times per day - this can add up to a huge number of errors.
Nobel Laureate Paul Modrich "spent his life trying to figure out how these mismatches…are corrected," Gustafsson said.
"He has found a system that we now know as the mismatch repair system."
This system repairs approximately 999 out of 1000 of these errors, which run the risk of creating mutations when cells divide and create new copies of themselves.
According to a Duke University news release on Modrich, approximately one mutation occurs every cell division and this would increase to 1000 mutations without this mismatch-repair mechanism.
One mutation per divided cell still an unsettling number, considering that 50-70 billion may happen in each of us during every 24-hour period. This must mean that most mutations are harmless and that other repair mechanisms, still being discovered, help to save the day.
A reporter at the Nobel announcement in Sweden pointed out that 2015 prize recipient Tomas Lindahl is actual a member of the Nobel Academy. She asked if he could have voted for the chemistry prize.
"Tomas Lindahl has not participated in this process, not attended any of the meetings, or contributed in written form to any of the evaluations," replied Göran Hansson, Secretary General, Royal Swedish Academy of Sciences.
She also asked asked how common it was that a Nobel Prize is given to a member of the academy.
"That's very rare indeed," Hansson replied, saying that he thought last happened for the chemistry prize in 1948 "and I wasn't even a member then," he joked.
A reporter at Nordic Chinese Times asked about the nomination process. Universities and individual scientists around the world receive a letter in English inviting nominations, replied Sara Snogerup Linse, chair of the Nobel Committee for chemistry.
"We pay special attention to make sure we include all parts of the world. We ask for nominations from the individual scientists at the university," Linse said.
Hannson said they made sure to send invitations on all continents with universities. "We don't cover Antarctica yet, but once there is a research university in Antarctica, we'll make sure they get the chance to nominate too," Hansson said.
Reactions from the Scientific Community
Marc Greenberg, professor of organic and bioorganic chemistry at Johns Hopkins University in Baltimore, Maryland shared these comments to Inside Science by phone:
"I can never predict these things, I don't even try. So when I turned on my Internet this morning and found out I was really excited."
"I think it's an incredibly important area and it's an area that is relatively new in the sense that it's less than half a century old."
"The Nobel Prize was given for discovering the structure of DNA [in 1953] and at that time no one thought, 'gee, do we have to worry about repairing DNA.'"
"There are potential health implications. DNA repair is yet another process that people are now becoming interested in in terms of targeting for therapeutic effects, so that's exciting as well."
Both Lindahl and Sancar's research influenced "my own research approaches this from the standpoint of damaged DNA."
"I remember reading an introduction to a monograph about 15 years ago from Tomas Lindahl where he postulated about the idea of utilizing molecules to inhibit basic excision repair enzymes. Certainly this has stuck with me."
Timothy Lohman, professor of biophysics at the Washington University School of Medicine in St. Louis, Missouri, provided this reaction:
"I think it's a great decision. The prize is for really three bodies of work where the individuals worked out the mechanism and identified the enzymes involved in three important repair pathways."
"It's really well deserved and exciting because all of these were really basic research studies that were important in their own right but also led to similar advancements in understanding repair in eukaryotes." Eukaryotes make up the group of living organisms, including mammals, that have more complex cells than bacteria.
"The initial studies started with bacteria and led into insights into eukaryotic repair."
Biophysicist Antoine van Oijen. a distinguished professor in the school of chemistry at University of Wollongong in Australia, wrote to Inside Science with his reaction to the 2015 Nobel Prize in chemistry:
"It is interesting to note that the Nobel committee gave the award for 'mechanistic studies of DNA repair' and not just for ‘studies of DNA repair.’ Big distinction that sends a powerful message to the field!"
"In biology, the term ‘mechanistic approach’ refers to those studies that reveal the mechanism of action with which proteins (or biomolecules in general) do certain things. It specifically refers to those studies that figure out exactly how a protein does something: by binding to such-and-such, triggering a movement of such-and-such domain, by moving to such-and-such place."
"This approach stands somewhat in contrast to an approach where you only figure out that a protein is needed for a particular process, without figuring out exactly what it does in that process. For example, you would observe that some process in a cell is halted if you remove the presence of a certain protein. That information is often valuable in defining key players in a process and can even let you screen for drug candidates that knock out a protein involved in disease process, but my argument is that in the end, you’d like to know exactly what it is that that protein does and how it does it. In other words: mechanistic understanding."
"The announcement of the awarding of the 2015 Chemistry Nobel Prize to the field of DNA repair is fantastic news for all those researchers working in the area of what we call ‘genomic maintenance’: the group of research fields that focusses on understanding how DNA is maintained. My group is very active in the area of DNA replication and DNA repair, both topics that revolve around the different ways with which complex protein machinery interact with DNA."
"One aspect of this Nobel Prize is that it signals a clear recognition of the value of classical, mechanistic enzymology: the use of biochemistry, genetics and molecular biology tools to understand at a molecular level how proteins and enzymes work. The work awarded has all been done a few decades ago. These days, it is sometimes difficult to convince funding bodies that achieving this level of mechanistic and molecular understanding using conventional mechanistic approaches is a critical step towards understanding disease mechanisms and designing strategies towards developing new drugs and therapeutics."