Production of VNPs, VLPs, and Chimeras - Viral Nanoparticles: Tools for Materials Science and Biomedicine - page 67

His tag can also be used to facilitate immobilization and assembly of
array structures as demonstrated for CPMV and Q

b

(Medintz et al. , 2005;

Udit et al. , 2008).

3. Deletions of amino acid side chains to facilitate higher level of

control over the number and sites available for bioconjugation.

If a
particle offers more attachment site than desired, sites can be removed
by mutagenesis. This has been demonstrated for CPMV, which has 300
addressable Lys side chains, five on each asymmetric unit. The asymmetric
unit of CPMV consists of one copy each of the S and L proteins (see Fig.
2.6). Systematic deletion of Lys side chains resulted in Lys-minus mutant
particles with uniquely reactive sites remaining (Chatterji et al. , 2004).

4. Alteration of surface charge to allow interactions with materials via

electrostatic interactions. An example is the alteration of the surface

charge of the N-terminus of the CCMV coat protein. The N-terminus is
involved in nucleic acid binding and packing and is highly positively
charged. Amino acid side chains were exchanged to generate an overall
negatively charged N-terminus. The electrostatically altered VNP
catalyzed the oxidation of Fe(II), leading to the formation of spatially
constrained iron oxide nanocrystals within the interior cavity of the
CCMV particles (Douglas

et al. , 2002).

5. Insertions of short peptide sequences or whole proteins. A whole

range of short peptide sequences and intact proteins have been
introduced into viral capsids for various applications. A number of
examples are listed here; the reader is referred to the respective chapters
to learn about the various chimeras. Antigenic peptides have been
introduced for vaccine development (Chapter 8). Targeting peptides
or proteins are used to deliver VNPs to specific molecular receptors
(Chapter 8), and various peptides that promote the nucleation of
inorganic materials have been incorporated into VNPs to facilitate their
mineralization and metallization for applications in materials science
(Chapter 6).

references

Ahlquist, P., French, R., Janda, M., and Loesch-Fries, L. S. (1984) Multicomponent RNA
plant virus infection derived from cloned viral cDNA, Proc. Natl. Acad. Sci. USA, 81 (22),

7066-7070.

Ahlquist, P., and Janda, M. (1984) cDNA cloning and in vitro transcription of the

complete brome mosaic virus genome, Mol. Cell. Biol. , 4 (12), 2876-2882.