A
team of researchers including Northwestern Engineering faculty has expanded the
understanding of how virus shells self-assemble, an important step toward
developing techniques that use viruses as vehicles to deliver targeted drugs
and therapeutics throughout the body.
By performing
multiple amino acid substitutions, the researchers discovered instances of
epistasis, a phenomenon in which two changes produce a behavior different from
the behavior that each change causes individually.
"We
found occurrences where two separate single amino acid changes caused the virus
shell to break or become really unstable, but making both changes together
produced a stable structure that functioned better than ever," said
Danielle Tullman-Ercek, associate professor of chemical and biological
engineering at the McCormick School of Engineering.
The
latest research builds on the team's progress by using SyMAPS to analyze
multiple amino acid changes within the MS2 particle, a requirement to
effectively manipulate virus shells in the future, Tullman-Ercek said.
Researchers studied every double amino acid combination along a polypeptide
loop located within the MS2 scaffold and measured how the virus scaffold was
affected.
One
factor producing epistasis was balancing the amino acid charges that were
substituted, said Tullman-Ercek, a member of Northwestern's Center for
Synthetic Biology. Swapping two positively charged amino acids, for instance,
caused the particle to repel and break apart, but balancing a single positive
amino acid change with a separate negative charge compensated the switch and
preserved stability.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
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