Changes in dynamical behavior of the retinoid X receptor DNA-binding domain upon binding to a 14 base-pair DNA half site

Differences in dynamics seen in retinoid X receptor (RXR) free in solution and in complex with a 14-base-pair DNA half-site have been investigated. Lipari-Szabo analysis was used with an axially symmetric tumbling model to gather information about the exchange contribution to the transverse relaxation rates. When DNA-binding had taken place the order parameters were slightly greater. Dynamics in the millisecond to microsecond range were seen more. The DNA-binding-induced folding transition takes place far from the DNA in an area involved in protein-protein interaction. Thus it may be that it is related to the cooperation of dimeric DNA-binding.