LIQUID CRYSTALS OF NANONUCLEIC ACIDS: HIERARCHICAL SELF-ASSEMBLY AS A ROUTE TO PREBIOTIC SELECTION, TEMPLATING, AND AUTOCATALYSIS

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This award by the Biomaterials program in the Division of Materials Research to University of Colorado at Boulder is cofunded by the Networks and Regulations Cluster (BIO/MCB). This research is motivated by our recent discovery of a variety of liquid crystal phases of nanoscale nucleic acids (nDNA and nRNA), i.e. of liquid crystals of duplex nucleic acids as short as 6 base pairs, an exciting, unexplored class of liquid crystal forming molecules. Key to this project is the finding that in a mixture of complementary and noncomplementary nDNA, the complementary DNA is found only in the LC domains. Thus in the nDNA liquid crystal phases, the coupled steps of duplexing, end-to-end stacking of duplexes, and liquid crystal phase ordering and separation create a structural gatekeeper that enables only duplexable DNA to enter. Molecules that do enter are then organized into a structure that if stabilized by covalent links should enhance their complementarity and the liquid crystal phase stability. Thus, whether is it possible for a liquid crystal phase to autocatalytically select, template, and replicate its constituent molecules, will be a principal topic of the proposed research, with the long-term goal of starting with multicomponent mixtures of polycyclic aromatics and developing processes that lead to LC formation by a self-selected subset of molecules. If this can be shown then it is a strong argument that the linear structure of DNA is itself a result of liquid crystal templating in early life. This project will enable the training of a group of graduate and undergraduate students in an exciting new area of nucleic acid biophysics. As part of the outreach activities, the researcher will collaborate with industry in the area of liquid crystal science applications in bioscience, renewable energy and related areas. It is widely believed by researchers studying the origin of life on Earth that life's first vestiges were systems of short self-replicating DNA-like molecules, that got up to about 30 bases long, emerging out of the so-called "primordial soup" of small prebiotic organic molecules in solution. Such an emergence is an "explosion" of complementarity, in which small molecules that are complementary, i.e., that can selectively stick together in pairs, seek each other out, collect together, and then react chemically into larger complementary units. In this project, the researcher has proposed the idea that condensation into liquid crystal droplets is a basic mechanism for selecting complementary molecules in such a process. With the addition of chemistry that couples up the short DNA into longer chains, condensation would strongly favor the lengthening of the already complementary DNA in the liquid crystal droplets. That is, complementarity would breed complementarity, in a process that selects for rod-shaped molecular assemblies, in order to promote liquid crystal order and phase separation. If this conjecture is correct, then we will have shown that the very linear polymer shape of DNA would have been templated by liquid crystal ordering in early life. The selection and reaction mechanisms explored are expected to open avenues to new kinds of hierarchically organized self assembled materials. The proposed educational activities included graduate curriculum development in soft condensed matter physics, and summer research activities such as Research Experience for Teachers, and Research Experience for Undergraduate students. Western Alliance to Expand Student Opportunities, Science Mathematics And Research for Transformation, and McNair programs providing undergraduate research opportunities for minorities and underrepresented groups are planned activities with this award.