G-quadruplexes are noncanonical nucleic acid structures formed by stacked guanosine tetrads. Despite their functional and structural diversity, a single consensus model is typically used to describe sequences with the potential to form G-quadruplex structures. We are interested in developing more specific sequence models for G-quadruplexes. In previous work, we functionally characterized each sequence in a 496-member library of variants of a monomeric reference G-quadruplex for the ability to bind GTP, promote a model peroxidase reaction, generate intrinsic fluorescence, and to form multimers. Here we used NMR to obtain a broad overview of the structural features of this library. After determining the 1H NMR spectrum of each of these 496 sequences, spectra were sorted into multiple classes, most of which could be rationalized based on mutational patterns in the primary sequence. A more detailed screen using representative sequences provided additional information about spectral classes, and confirmed that the classes determined based on analysis of 1H NMR spectra are correlated with functional categories identified in previous studies. These results provide new insights into the surprising structural diversity of this library. They also show how NMR can be used to identify classes of sequences with distinct mutational signatures and functions.

• Keywords
• DNA, G-quadruplex, Multimeric structures, NMR,
• MeSH
• G-Quadruplexes * MeSH
• Guanosine Triphosphate chemistry   metabolism   MeSH
• Magnetic Resonance Spectroscopy methods   MeSH
• Mutation MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Guanosine Triphosphate MeSH

For many decades it was thought that information storage and information transfer were the main functions of nucleic acids. However, artificial evolution experiments have shown that the functional potential of DNA and RNA is much greater. Here I provide an overview of this technique and highlight recent advances which have increased its potency. I also describe how artificial evolution has been used to identify nucleic acids with extreme functions. These include deoxyribozymes that generate unusual products such as light, tiny motifs made up of fewer than ten nucleotides, ribozymes that catalyze complex reactions such as RNA polymerization, information-rich sequences that encode overlapping ribozymes, motifs that catalyze reactions at rates too fast to be followed by manual pipetting, and functional nucleic acids which are active in extreme conditions. Such motifs highlight the limits of our knowledge and provide clues about as of yet undiscovered functions of DNA and RNA.

• Keywords
• aptamer, deoxyribozyme, in vitro selection, ribozyme, supernova deoxyribozyme,
• MeSH
• DNA, Catalytic * metabolism   MeSH
• DNA MeSH
• Nucleic Acid Conformation MeSH
• Nucleotides MeSH
• Nucleic Acids * MeSH
• RNA, Catalytic * metabolism   MeSH
• RNA genetics   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• DNA, Catalytic * MeSH
• DNA MeSH
• Nucleotides MeSH
• Nucleic Acids * MeSH
• RNA, Catalytic * MeSH
• RNA MeSH