Structural Polymorphism of G-Rich DNA and its Orientation to Inorganic Nanoparticles

摘要

G-quadruplex forming sequences have been found to be prevalent in all eukaryotic chromosomes, particularly enriched in telomeric regions, insulin-linked polymorphic region, regulatory sequences of muscle-specific genes, etc. G-rich DNAs present polymorphic conformations depending on the sequence, cation species, molecular crowding conditions, etc. Interconversion mechanism between the G-quadruplex and the Watson-Crick (WC) duplex structures is fundamental to understand how the gene transcription is regulated in vivo and how to design potent anticancer drugs in the field of medicinal chemistry, as well as how to construct nanomolecular machines based on supramolecular assembly of nucleic acids. Based on our investigations on the effects of cation species, pH and small ligands on the structural competition of telomeric G-quadruplex and its related Waston-Crick duplex by using circular dichroism, ESI-MS and molecular modeling methods, we studied the size distribution and morphology of Ag nanocrystals formed under the orientation of G-rich DNA sequence A8G12 versus the competing duplex formed by A8G12 and its complementary strand. These DNA-templated silver nanoparticles show interesting catalytic performance, dependent on the DNA templates. On the other hand, we designed one series of G-rich DNA sequences to construct a novel self-assembled G-ribbon with sticky bands and utilize this G-ribbon to functionalize amino-coated silica nanoparticles. More interesting, leaf-vein nanostructures with regular branch intervals are also organized based on the self-recognition of sticky bands of G-ribbon coupled with functionalized nanoparticles.