Physics of DNA: unravelling hidden abilities encoded in the structure of ‘the most important molecule’

A comprehensive article “Structure and Interactions of Biological Helices”, published in 2007 in Reviews of Modern Physics, overviewed various aspects of the effect of DNA structure on DNA–DNA interactions in solution and related phenomena, with a thorough analysis of the theory of these effects. Here, an updated qualitative account of this area is presented without any sophisticated ‘algebra’. It overviews the basic principles of the structure-specific interactions between double-stranded DNA and focuses on the physics behind several related properties encoded in the structure of DNA. Among them are (i) DNA condensation and aptitude to pack into small compartments of cells or viral capcids, (ii) the structure of DNA mesophases, and (iii) the ability of homologous genes to recognize each other prior to recombination from a distance. Highlighted are some of latest developments of the theory, including the shape of the ‘recognition well’. The article ends with a brief discussion of the first experimental evidence of the protein-free homology recognition in a ‘test tube’.