Duplex structure of a minimal nucleic acid.
The crystal structure of an 8-mer (S)-GNA duplex is presented. As a tool for phasing, the anomalous diffraction of two copper(II) ions within two artificial metallo-base pairs was employed. The duplex structure confirms a canonical Watson-Crick base pairing scheme of GNA with antiparallel strands. The duplex secondary structure is distinct from canonical A- and B-form nucleic acids and can be described as a right-handed helical ribbon wrapped around the helix axis, resulting in a large hollow core. Most intriguingly, neighboring base pairs slide strongly against each other, resulting in extensive interstrand base-base hydrophobic interactions along with unusual hydrophobic intrastrand interactions of nucleobases with their backbone. These results reveal how a minimal nucleic acid backbone can support highly stable Watson-Crick-like duplex formation.
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein Strasse, D-35043 Marburg, Germany.
Mark K
MK
Schlegel
Lars-Oliver
LO
Essen
Eric
E
Meggers
D020029:Base Pairing; D003300:Copper; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*
D009841:Oligonucleotides; D003300:Copper