URGENT - for distribution

[CM ICTP - Trieste]

									07/02

JOINT ICTP/SISSA CONDENSED MATTER SEMINARS
Academic Year 2006/07





Seminar Room - Main Building (first floor)



Wednesday, 23 May -     4:00 p.m.



A.A. KORNYSHEV   ( Imperial College London )


" DNA interaction, recognition and aggregation.  Love at first sight "


Abstract

How can meters of genetic material be packed in mammalian sperm and 
phage heads?  Why do some ions condense DNA, while others do not?  Why 
does DNA change its structure in dense aggregates?  These and other 
questions, including a mechanism for snap-shot genegene recognition in 
recombination of homologous genes suggested by Kornyshev and Leikin are 
addressed within an ongoing research program of a ‘transatlantic’ team 
at the Departments of Chemistry and Molecular Biosciences of Imperial 
College London, and the Physical Biochemistry Group of the Institute of 
Child Health and Human Development of the National Institute of Health 
(Bethesda, MD, USA).  This project is based on Kornyshev-Leikin theory 
of interaction of helical macromolecules in solutions. In line with a 
wealth of experimental data (such as the observed poly- and 
meso-morphism of DNA assemblies, and the measured decay range of 
repulsive forces between various helical macromolecules) this theory 
was recently extended to the statistical mechanics of DNA columnar and 
cholesteric phases, and DNA mechanics - mapped on forefront models of 
nonlinear physics (A. Cherstvy, A. Kornyshev, D.J. Lee, S. Leikin, A. 
Wynveen).  One of the recent results was the experimental proof of 
azimuthal correlations between DNA in hydrated aggregates (A.A. 
Kornyshev, D.J. Lee, S. Leikin, A. Wynveen, S. Zimmerman), predicted by 
the theory. The latest experiments of Imperial-NIH team (G. Baldwin, N. 
Brooks, A. Goldar, S. Leikin, R. Robson, J. Seddon) has recently 
approved existence of the physical mechanism of homology recognition in 
protein free environment, predicted by KL in 2001. The effect of 
homology recognition is what presumably warrants against errors in 
homologous recombination of genes – the process responsible for 
evolution and genetic diversity, as well DNA repair. Thus understanding 
the recognition mechanism may result in the future in understanding how 
to avoid such errors that themselves are responsible for a number of 
genetically determined diseases, such as cancer and Atzheimer’s on one 
hand, or aging on the other hand.
This talk will introduce the audience to the principles of the theory, 
present some of its main results, and review the latest experimental 
findings.  An interested listener is referred to a detailed article 
which will be published in the June issue of Reviews of Modern Physics: 
A.A. Kornyshev, D.J. Lee, S. Leikin, and A. Wynveen: Structure and 
interactions of biological helices, and the original publications, 
listed below.


Theory of interaction between helical molecules
A.A.Kornyshev and S.Leikin, J.Chem.Phys. 1997,107, 3656.

Symmetry laws for interaction between helical macromolecules.
A.A.Kornyshev and S.Leikin, Biophys.J., 1998, 75, 2513.

Helical symmetry and electrostatic interaction of macromolecules in 
dense aggregates. An impetus for DNA poly- and meso-morphism.
A.A.Kornyshev and S.Leikin, Proc.Natl.Acad.Sci.USA. 1998, 95, 13579.

Electrostatic zipper motif for DNA aggregation.
A.A.Kornyshev and S.Leikin, Phys.Rev.Lett., 1999, 82, 4138.

A twist in chiral interaction between biological helices.
A.A.Kornyshev and S.Leikin, Phys.Rev.Lett. 2000, 84, 2537.

Electrostatic interaction between long, rigid helical macromolecules at 
all interaxial angles
A.A.Kornyshev and S.Leikin, Phys.Rev.E, 2000, 62, 2576.

Sequence recognition in pairing of DNA duplexes.
A.A.Kornyshev and S.Leikin, Phys.Rev.Lett. 2001, 86, 3666. DNA need not 
unzip.-
http://focus.aps.org/v7/st19.html

Chiral electrostatic interactions and cholesteric liquid crystals of 
DNA.
A.A.Kornyshev, S.Leikin, and S.Malinin, European Phys.J. E (Soft 
Matter) 2002, 7, 83.

Phase behavior of columnar DNA assemblies.
H.M.Harreis, A.A.Kornyshev, C.N.Likos, H.Loewen, and G.Sutmann, 
Phys.Rev.Lett. 2002, 89, art.#18303.

Temperature-dependent DNA condensation triggered by rearrangement of 
adsorbed cations.
A.G. Cherstvy, A.A.Kornyshev, S.Leikin, J.Phys.Chem.2002,106, 13362.

Torsional Deformation of Double Helix in Interaction and aggregation of 
DNA.
A.G.Cherstvy, A.A.Kornyshev, and S.Leikin, J.Phys.Chem.B, 2004, 108, 
6508.

Nonlinear effects in torsional adjustment of interacting DNA.
A.Kornyshev and A.Wynveen,. Phys.Rev.E, 2004, 69, #041905, 1-14.

DNA-DNA interaction beyond the ground state.
D.J.Lee, A.Wynveen, and A.A.Kornyshev, Phys. Rev. E, 2004, 70, #051913, 
1-12

Statistical mechanics of DNA assemblies.
A.Wynveen, D.J.Lee, and A.A.Kornyshev, Eur.Phys.J. E, 2005, 16, 303.

Torsional fluctuations in columnar DNA assemblies.
D.J.Lee and A.Wynveen, J.Phys: Condensed Matter, 18, 786 (2006).

DNA melting in aggregates: impeded or facilitated?
A.G.Cherstvy and A.A.Kornyshev, J.Phys.Chem.B, 2004, 108, 6508.

Direct observation of azimuthal correlations between DNA in hydrated 
aggregates
A.A.Kornyshev, D.J.Lee, S.Leikin, A.Wynveen, S.Zimmerman, 
Phys.Rev.Lett. 2005, 95,#148102.