Template-Assisted Assembly of Hybrid DNA/RNA Nanostructures Using Branched Oligodeoxy- and Oligoribonucleotides.

A template-assisted assembly approach to a C fullerene-like double-stranded DNA polyhedral shell is proposed. The assembly employed a supramolecular oligonucleotide dendrimer as a 3D template that was obtained via the hybridization of siRNA strands and a single-stranded DNA oligonucleotide joined to three- or four-way branched junctions. A four-way branched oligonucleotide building block (a ) was designed for the assembly of the shell composed of three identical self-complementary DNA single strands and a single RNA strand for hybridization to the DNA oligonucleotides of the template.

Amyloidogenicity as a driving force for the formation of functional oligomers.

Insoluble amyloid fibrils formed by self-assembly of amyloidogenic regions of proteins have a cross-β-structure. In this work, by using targeted molecular dynamics and rigid body simulation, we demonstrate that if a protein consists of an amyloidogenic region and a globular domain(s) and if the linker between them is short enough, such molecules cannot assemble into amyloid fibrils, instead, they form oligomers with a defined and limited number of β-strands in the cross-β core. We show that this blockage of the amyloid growth is due to the steric repulsion of the globular structures linked to amyloidogenic regions.

Establishment of Constraints on Amyloid Formation Imposed by Steric Exclusion of Globular Domains.

In many disease-related and functional amyloids, the amyloid-forming regions of proteins are flanked by globular domains. When located in close vicinity of the amyloid regions along the chain, the globular domains can prevent the formation of amyloids because of the steric repulsion. Experimental tests of this effect are few in number and non-systematic, and their interpretation is hampered by polymorphism of amyloid structures.