The traditonal belief about the function of DNA centers around the fact that it stores an organism’s genetic information and controls how proteins are released and produced. Now scientists have discovered that DNA in essence has another previously undiscovered function and that is to control genes.
Researchers attribute this second function to a second code hidden within DNA which contains information that changes how scientists read the instructions contained in DNA and interpret mutations to make sense of health and disease.
“For over 40 years we have assumed that DNA changes affecting the genetic code solely impact how proteins are made,” said Stamatoyannopoulos. “Now we know that this basic assumption about reading the human genome missed half of the picture. These new findings highlight that DNA is an incredibly powerful information storage device, which nature has fully exploited in unexpected ways.”
The genetic code uses a 64-letter alphabet called codons. Some codons dubbed duons by the UW team, can have two meanings, one related to protein sequence, and one related to gene control. These two meanings seem to have evolved in concert with each other. The gene control instructions appear to help stabilize certain beneficial features of proteins and how they are made.
“The fact that the genetic code can simultaneously write two kinds of information means that many DNA changes that appear to alter protein sequences may actually cause disease by disrupting gene control programs or even both mechanisms simultaneously,” said Stamatoyannopoulos.
The discovery raises obvious concerns about the influence of epigenetics (environmental influences that change the expression of the genetic code) and the current new development of using RNA interference to genetically modify organisms to carry a certain trait, which can impact on DNA changes.
A. B. Stergachis, E. Haugen, A. Shafer, W. Fu, B. Vernot, A. Reynolds, A. Raubitschek, S. Ziegler, E. M. LeProust, J. M. Akey, J. A. Stamatoyannopoulos. Exonic Transcription Factor Binding Directs Codon Choice and Affects Protein Evolution. Science, 2013; 342 (6164): 1367 DOI: 10.1126/science.1243490