Self - assembling protein icosahedron
Scientists have created artificial viruses without DNA
Biochemists from the University of Washington have modeled and then synthesized proteins that are able to combine to form an icosahedron.
An icosahedron is a regular hexahedron, each face of which is an equilateral triangle. Geodesic domes, fullerene molecules, and soccer balls have the shape of a truncated icosahedron.
Such complex molecules, whose shape corresponds to the shells of many viruses, can be used as a transport for the delivery of drugs and other active substances to cancer cells. Article by Hsia et al. The design of a hyperstable 60-subunit protein icosahedron is published in the journal Nature.
Drawing from the UW Medicine press release
Self-assembling protein icosahedral shell designed – VM
The icosahedron was constructed from 60 protein blocks, the amino acid sequences of which were selected by scientists from the Protein Data Bank database containing a collection of three-dimensional structures of many proteins. In total, biologists have tested 300 different proteins to see if they are able to form the desired shape. The researchers performed the necessary calculations in a special program Symmetric RosettaDesign, which evaluated various parameters of protein blocks and determined whether it was possible to build an icosahedron from them.
For the selected proteins, the corresponding genes were determined, which were transported to Escherichia coli Escherichia coli cells using plasmids. Based on the embedded DNA sequences, the bacteria synthesized protein blocks, which were then extracted from E.coli and placed in a special solution, where the self-assembly of icosahedra took place.
Electron microscopy has shown that the size of the obtained particles is 14 nanometers, and their structure corresponds to the one that was originally obtained using computer modeling.
According to scientists, the ability to design proteins capable of self-organizing into predetermined structures opens the way to the creation of microscopic containers that transport larger volumes of matter than previously developed capsules. Such capsules can be used for targeted drug delivery to affected organs and tissues, which allows you to destroy defective cells without affecting healthy ones. In this way they resemble empty capsids – protein shells, which in real viruses contain infectious DNA or RNA.
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