Coarse-Grained Model of Entropic Allostery

Many signalling functions in molecular biology require proteins bind to substrates such as DNA in response to environmental signals such as the simultaneous binding to a small molecule. Examples are repressor proteins which may transmit information via a conformational change in response to the ligand binding. An alternative entropic mechanism of ``allostery'' suggests that the inducer ligand changes the intramolecular vibrational entropy not just the static structure. We present a quantitative, coarse-grained model of entropic allostery that suggests design rules for internal cohesive potentials in proteins employing this effect. It also addresses the issue of how the signal information to bind or unbind is transmitted through the protein. The model may be applicable to a wide range of repressors and also to signalling in transmembrane proteins.