Chemistry

Mimicking Rodlike Viruses

+ See all authors and affiliations

Science  10 May 2013:
Vol. 340, Issue 6133, pp. 662
DOI: 10.1126/science.340.6133.662-a
CREDIT: Y. RUFF ET AL., J. AM. CHEM. SOC. 135, 16 (2013) © 2013 AMERICAN CHEMICAL SOCIETY

The self-assembly of one-dimensional (1D) structures that have a precise length can be particularly difficult because such assemblies are prone to aggregation, even though these structures are readily formed by rodlike viruses such as the tobacco mosaic virus. Ruff et al. have mimicked the assembly of 1D filamentous viruses by encapsulating double-stranded DNA—both linear strands and supercoiled circular plasmids—in water. They used a triblock structure to mimic the protein coat. A cationic spermine unit that binds to DNA is attached to a peptide that forms a compact coiled structure. The other end of the peptide bears a polyethylene glycol (PEG) tail that creates a hydrophilic exterior structure. These mushroom-shaped capsomers bind and encapsulate DNA (for DNA strands 1200 base pairs long, about 1.2 to 1.5 units bind per base pair) and can form structures up to 1.6 µm in length. The homogeneity of the linear structures formed improved with longer PEG tails (5000 versus 2000 monomers), as determined by small-angle x-ray scattering and transmission electron microscopy studies. The larger structures formed by the longer PEG chains appear to stiffen the structure and allow the DNA to work effectively as a linear template, and decrease the fraction of shorter structures that form when DNA buckles and folds back on itself.

J. Am. Chem. Soc. 135, 6211 (2013).

Navigate This Article