  Signal transmission at the molecular level in many biological complexes
occurs through allosteric transitions. They describe the response a complex to
binding of ligands at sites that are spatially well separated from the binding
region. We describe the Structural Perturbation Method (SPM), based on phonon
propagation in solids, that can be used to determine the signal transmitting
allostery wiring diagram (AWD) in large but finite-sized biological complexes.
Applications to the bacterial chaperonin GroEL-GroES complex shows that the AWD
determined from structures also drive the allosteric transitions dynamically.
Both from a structural and dynamical perspective these transitions are largely
determined by formation and rupture of salt-bridges. The molecular description
of allostery in GroEL provides insights into its function, which is
quantitatively described by the Iterative Annealing Mechanism. Remarkably, in
this complex molecular machine, a deep connection is established between the
structures, reaction cycle during which GroEL undergoes a sequence of
allosteric transitions, and function in a self-consistent manner.
