Nucleic Acids Research Advance Access originally published online on July 28, 2008
Nucleic Acids Research 2008 36(15):5050-5060; doi:10.1093/nar/gkn459
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Nucleic Acids Research, 2008, Vol. 36, No. 15 5050-5060
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Chemistry and Synthetic Biology |
Assembling of G-strands into novel tetra-molecular parallel G4-DNA nanostructures using avidin–biotin recognition
1Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978, 2Physical Chemistry Department, 3Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel and 4The Center for Nanoscience and Nanotechnology, Tel Aviv University
*To whom correspondence should be addressed. Tel: 972 3 6407138; Fax: 972 3 6406834; Email: s2shak{at}post.tau.ac.il
Correspondence may also be addressed to Danny Porath. Tel: 972 2 6586948; Fax: 972 2 6586987; Email: porath{at}chem.ch.huji.ac.il
Received May 4, 2008. Revised July 1, 2008. Accepted July 2, 2008.
We describe a method for the preparation of novel long (hundreds of nanometers), uniform, inter-molecular G4-DNA molecules composed of four parallel G-strands. The only long continuous G4-DNA reported so far are intra-molecular structures made of a single G-strand. To enable a tetra-molecular assembly of the G-strands we developed a novel approach based on avidin–biotin biological recognition. The steps of the G4-DNA production include: (i) Enzymatic synthesis of long poly(dG)-poly(dC) molecules with biotinylated poly(dG)-strand; (ii) Formation of a complex between avidin-tetramer and four biotinylated poly(dG)-poly(dC) molecules; (iii) Separation of the poly(dC) strands from the poly(dG)-strands, which are connected to the avidin; (iv) Assembly of the four G-strands attached to the avidin into tetra-molecular G4-DNA. The average contour length of the formed structures, as measured by AFM, is equal to that of the initial poly(dG)-poly(dC) molecules, suggesting a tetra-molecular mechanism of the G-strands assembly. The height of tetra-molecular G4-nanostructures is larger than that of mono-molecular G4-DNA molecules having similar contour length. The CD spectra of the tetra- and mono-molecular G4-DNA are markedly different, suggesting different structural organization of these two types of molecules. The tetra-molecular G4-DNA nanostructures showed clear electrical polarizability. This suggests that they may be useful for molecular electronics.