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Protein add-ons
Protein
functionalization of DNA has so far utilized a limited number of
orthogonal approaches, using nucleic acid-protein conjugates (Wilner,
2009), aptamer-protein interactions (Rinker, 2008), antibody-antigen
interactions (He, 2006; Williams, 2007) and streptavidin-biotin system
(Yan, 2003; Kuzuya, 2009; Voight, 2010). Sacca and co-workers
demonstrated the use of three different protein tags at the same time:
biotin-streptavidin interaction and two suicide ligands for their
specific enzymes (Sacca, 2010). These systems are based mainly on
incorporation of specifically labeled oligonucleotides.
We proposed a more general approach for position-specific protein
binding to the surface of DNA origami, which has to comply with several
criteria:
- strong binding affinities (Kd preferably in the nanomolar
or subnanomolar range),
- simultaneous
binding of several molecules using the same approach and reaction
conditions,
- technological
feasibility in terms of cost and technology used.
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<img
style="padding: 0pt 0pt 5px; width: 552px; height: 218px;"
alt="" src="http://openwetware.org/images/d/d7/ShemaZNFdolg.jpg"> |
| Figure 2: Schematic
representation of six-finger ZFP attached to its DNA target. Each zinc finger motif
composed of ββα fold binds specifically to 3 bp of DNA. |
Last year <a
href="http://2010.igem.org/Team:Slovenia">Team Slovenia at
iGEM2010</a> competition proposed a scaffold-assisted
biosynthetic pathway utilizing linear dsDNA as a program and zinc
finger proteins as binding domains. This approach increased production
of trans-resveratrol in bacteria 5-fold in the presence of DNA program
which arranged the enzymes in the correct order (Conrado, 2011).
Zinc finger proteins (ZFPs)
are the most widespread and best characterized DNA-binding protein
domains to date. These small structural motifs form coordination bonds
with zinc cations to stabilize their ββα fold. Each zinc finger
recognizes and binds
three consecutive base pairs of a double stranded DNA in a
sequence-dependent manner (Figure
2). Their specificity is based on interactions between
amino acid side chains of the zinc finger α-helix and the DNA.
Moreover, zinc finger
proteins can be designed by direct protein fusion of several successive
zinc fingers which gives us access to an almost unlimited pool of
proteins (at least 700 well characterized in the ZiFDB database), which
specifically and predictably target distinct DNA sequences. Binding
affinity of such zinc finger proteins to their target DNA
sequences
depends mainly on the number of successive zinc fingers used.
Therefore, six finger proteins had been reported to have subnanomolar
and even picomolar
binding affinities.
A DNA origami
add-on approach proposed by BioNanoWizards
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<img
style="font-family: Arial; width: 890px; height: 663px; padding: 0 0 8px 0;" alt=""
title="Beach house"
src="http://openwetware.org/images/d/da/Protein_add-ons.png"> |
| Figure 3: Position
specific
functionalization of DNA origami with selected protein functions. Step
1: Desired functional protein domains are combined with any of the
characterized 700 ZFPs into chimeric proteins. Step 2: Staples at
selected positions on DNA origami are replaced with staples with added
hairpin that incorporates the recognition sequence of the ZFPs selected
in step 1, DNA origami with modified staples is annealed. Step 3:
ZFP-functional domain chimeras are added to DNA origami and bind to the
selected positions. |
Full potential of zinc
fingers could be realized by fusion to selected functional protein
domains, e.g. nucleases, recombinases and others, which have already
been used to engineer genomes. In such systems zinc finger proteins
serve for targeting functional domains to specific sites on DNA. This
idea set the foundation for protein
DNA origami add-ons. By inserting
DNA hairpins into staple strands at specific positions on DNA origami,
one can easily direct binding of such functional domains through zinc
finger protein-target DNA interactions. Such an approach offers
immediate high-tech
applications such as <a
href="http://openwetware.org/wiki/Biomod/2011/Slovenia/BioNanoWizards/applabonchip">lab-on-a-nanochip</a>,
<a
href="http://openwetware.org/wiki/Biomod/2011/Slovenia/BioNanoWizards/appbiosensors">nanobiosensors</a>,
sequential biosynthetic route setups or <a
href="http://openwetware.org/wiki/Biomod/2011/Slovenia/BioNanoWizards/appbiosynthteticcompartments">construction
of
biosynthetic organelles</a>.
DNA binding proteins
might be also used for structural purposes, e.g. to combine several DNA
nanostructures via protein tethers, containing ZFPs, which is described
in the next section.
- Conrado RJ, Wu GC, Boock JT, Xu H, Chen SY, Lebar T, Turnšek J, Tomšič
N, Avbelj M, Gaber R, Koprivnjak T, Mori J, Glavnik V, Vovk I, Benčina
M, Hodnik V, Anderluh G, Dueber JE, Jerala R, DeLisa MP (2011)
DNA-guided assembly of biosynthetic pathways promotes improved
catalytic efficiency. Nucleic
Acids Res. in press
- He Y, Tian Y, Ribbe AE, Mao C (2006) Antibody Nanoarrays with a pitch
of 20 nanometers J. Am.
Chem. Soc. 128: 12664-12665.
-
Kuzuya A, Kimura M, Numajiri N, Koshi N, Ohnishi T, Okada F, Komiyama M
(2009) Precisely programmed and robust 2D streptavidin nanoarrays by
using periodical nanometer-scale wells embedded in DNA origami assembly
ChemBioChem
10: 1811-1815.
- Rinker S, Ke Y, Liu Y, Chhabra R (2008) Self-assembled DNA
nanostructures for distance-dependent multivalent ligand-protein
binding Nat. Nanotech.
3: 418-422.
-
Sacca B, Meyer R, Erkelenz M, Kiko K, Arndt A, Schroeder H, Rabe KS,
Niemeyer CM (2010) Orthogonal protein decoration of DNA origami. Angew. Chem. 49:
9378-83.
-
Voight NV, Torring T, Rotaru A, Jacobsen MF, Ravnsbaek JB, Subramani R,
Mamdouh W, Kjems J, Mokhir A, Besenbacher F, Gothelf KV (2010) Single
molecule chemical reactions on DNA origami Nat. Nanotechnol.
5:200-203.
-
Williams BAR, Lund K, Liu Y, Yan H, Chaput JC (2007) Self-assembled
peptide nanoarrays: an approach to studying protein-protein
interactions Angew. Chem.
119: 3111-3114.
-
Wilner OI, Weizmann Y, Gill R, Lioubashevski O, Freeman R, Willner I
(2009) Enzyme cascades activated on topologically programmed DNA
scaffolds Nat. Nanotech.
4: 249-254.
-
Yan H, Park SH, Finkelstein G, Reif JH, LaBean TH (2003) Design and
construction of double-decker tile as a route to three-dimensional
periodic assembly of DNA Science
301: 1882-1884.
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