New study hints at spontaneous appearance of primordial DNA (April 2015)
The self-organization properties of DNA-like molecular fragments four billion years ago may have guided their own growth into repeating chemical chains long enough to act as a basis for primitive life, says a new study by Center members at the University of Colorado Boulder and the University of Milan.
The findings suggest a novel scenario for the non-biological origins of nucleic acids, which are the building blocks of living organisms. Co-authors of a recently published paper on the subject include doctoral students Tommaso Fraccia and Gregory Smith, postdoctoral researchers Giuliano Zanchetta and Youngwooo Yi, and Center Investigators Tommaso Bellini of the University of Milan, who led the study, and David Walba and Noel Clark from CU Boulder.
For several years the group has been exploring the hypothesis that the way in which DNA emerged on the early Earth lies in its structural properties and its ability to self-organize. In the pre-RNA world, the spontaneous self-assembly of fragments of nucleic acids (DNA and RNA) may have acted as a template for their chemical joining into polymers, which are substances composed of a large number of repeating units. This new research demonstrates that the spontaneous self-assembly of DNA fragments just a few nanometers in length into ordered liquid crystal phases has the ability to drive the formation of chemical bonds that connect together short DNA chains to form long ones, without the aid of biological mechanisms.
Droplet of condensed nano-DNA and within it smaller drops of its liquid crystal phase, illuminated at left between crossed polarizers. The liquid crystal droplets act as "micro-reactors" where short DNA can join together into long polymer chains without the aid of biological mechanisms.
The authors propose that something analogous may have happened on the early Earth when the first DNA-like molecular fragments appeared, providing a pre-RNA route to the RNA world.
This work was published in "Abiotic ligation of DNA oligomers templated by their liquid crystal ordering," T.P. Fraccia, G.P. Smith, G. Zanchetta, E. Paraboschi, Y. Yi, D.M. Walba, G. Dieci, N.A. Clark and T. Bellini, Nature Communications 6, 6424 (2015).
Read the press release.